In the Biblical sense, "icon" and "image" are synonymous. The word icon comes directly from the Greek εἰκών (eikōn). In the Septuagint, it represents the Hebrew word צלמ (Masoretic צֶ֫לֶם; ṣě·lěm), as in Genesis 1:26:
And God said, Let us make man in our image [eikōn], after our likeness
The Law of Moses explicitly required use of representations in worship:
And thou shalt make two cherubims of gold, of beaten work shalt thou make them, in the two ends of the mercy seat. And make one cherub on the one end, and the other cherub on the other end: even of the mercy seat shall ye make the cherubims on the two ends thereof. And the cherubims shall stretch forth their wings on high, covering the mercy seat with their wings, and their faces shall look one to another; toward the mercy seat shall the faces of the cherubims be. And thou shalt put the mercy seat above upon the ark; and in the ark thou shalt put the testimony that I shall give thee. And there I will meet with thee, and I will commune with thee from above the mercy seat, from between the two cherubims which are upon the ark of the testimony, of all things which I will give thee in commandment unto the children of Israel.
I'm not sure if one would characterize this as something that simply "helped" the Jews to worship, though. The purpose, as the text states, was to provide a physical point where God would meet and commune with them.
The Jews were given another command to create an image of a serpent, though not specifically for worship:
And the Lord said unto Moses, Make thee a fiery serpent, and set it upon a pole: and it shall come to pass, that every one that is bitten, when he looketh upon it, shall live. And Moses made a serpent of brass, and put it upon a pole, and it came to pass, that if a serpent had bitten any man, when he beheld the serpent of brass, he lived.
This passage is also relevant to the discussion (see below), however, since the question could be understood to insinuate that the use of images in worship is somehow "non-Biblical".
Excursus on iconoclasm
In what follows, I would like to address what I think is a faulty premise in the question: that for the Orthodox, icons serve as nothing more than something to 'lift up their minds from earthly things to the heavenly things'. Their purpose is actually much more profound than that. I cannot speak for Roman Catholics, though the sources which I cite below are also considered Church Fathers by the Roman Catholic Church and all date to before the Schism of 1054, when the Eastern Orthodox and Roman Catholics mutually separated.
The iconoclasts of the 8th and 9th centuries, as well as the neo-iconoclasts of today, frequently cite Exodus 20:4 as grounds from excluding any and all images from worship:
Thou shalt not make unto thee any graven image, or any likeness of any thing that is in heaven above, or that is in the earth beneath, or that is in the water under the earth
Interestingly, the Hebrew word translated as image in this verse is not the same Hebrew word that appears in Genesis 1:26. Here, פֶּ֫סֶל (pě·sěl), not צֶ֫לֶם (ṣě·lěm) is used. Many English translations translate the pě·sěl as "graven image" (KJV) or "formed image" (ESV), but some actually use the word that appears in the Septuagint: idol (Gr. εἴδωλον - eidōlon).
The arguments employed by the iconoclasts of the first millennium were much more sophisticated than those offered by the neo-iconoclasts of today, who generally simply parrot Exodus 20:4, maintaining that it is some kind of self-evident "proof text". Theodore the Studite (759-826) dismisses this argument early on in his treatise, On the Holy Icons (and then moves on to more substantive objections in the remaining 150 sections):
"The erection of images is completely forbidden," the heretics say, "in the Scripture; for it says, You shall not make an idol for yourself, nor any likeness of whatever is in the heaven above or on the earth below or in the heavens above or on the earth below or in the waters under the earth. You shall not venerate them, nor shall you worship them, for I am the Lord your God."
When and to whom were these words spoken? Before the age of grace, and to those who were confined under the Law,1 and were being taught the monarchy of one divine person; when God had not yet been revealed in the flesh, and the men of antiquity were being protected against foreign idols. This law had to be made for those who through their forefather Abraham had formed a chosen people and fled the abyss of polytheism, because there is one God and Lord of all, whom no man has ever seen or can see2, as it is written. For Him there is no designation, no likeness, no circumspection, no definition, nothing at all of what comes within the comprehension of the human mind. The words of the prophet make this very clear: To whom did you liken the Lord, or with what likeness did you compare Him?3 I pass over the fact that what was utterly forbidden in the case of God was not utterly forbidden in every case. For He who had given the prohibition to the hierophant Moses immediately commanded him: You shall make two cherubim of gold, of hammered works, on the two ends of the mercy seat ...4
Theodore then puts the serpent of Moses into context:
And in the book of Leviticus, the Lord says to Moses, Make a serpent for yourself, and set it on a pole ... Now you see the whole teaching of Scripture; although the angels are not solid like us; and although the serpent differs from us by its reptilian shape, nevertheless it was received figuratively as a symbol of Christ.5 If God formerly condescended to be symbolized as a serpent in order to heal those who were bitten, how could it not be pleasing to Him and appropriate to set up the image of the bodily from which has been His since He became man? And if the symbol in animal form cured those who had been bitten by its sight alone, how could the holy representation of Christ's very form do otherwise than hallow those who see it?5
Iconoclasm arose during the first millennium in part due to the influence of Islam. By the 9th century, the geographical territory of three of the five ancient Sees of the Church - Jerusalem, Alexandria, and Antioch - were under the control of Muslims. This reversal in political fortune after several centuries of expansion led some Byzantine emperors to introspection as to what might be going wrong. The strict Muslim prohibition against holy images was one aspect that they considered. Was this Muslim doctrine somehow placing Muslims in more favor with God than Christians? Ironically, it was in areas under Muslim control where Christians had the most freedom to write in defense of icons. Iconoclasm, though previously condemned by Church Fathers such as John of Damascus (676-749) and Theodore the Studite, was finally and definitively condemned at the 7th Ecumenical Council at Nicaea in 787, which declared:
We define that the holy icons, whether in colour, mosaic, or some other material, should be exhibited in the holy churches of God, on the sacred vessels and liturgical vestments, on the walls, furnishings, and in houses and along the roads, namely the icons of our Lord God and Saviour Jesus Christ, that of our Lady the Theotokos, those of the venerable angels and those of all saintly people. Whenever these representations are contemplated, they will cause those who look at them to commemorate and love their prototype. We define also that they should be kissed and that they are an object of veneration and honour, but not of real worship, which is reserved for Him Who is the subject of our faith and is proper for the divine nature. The veneration accorded to an icon is in effect transmitted to the prototype; he who venerates the icon, venerated in it the reality for which it stands.
Despite the affirmation of the 7th Ecumenical Council, a remnant of iconoclasm survived within part of the Byzantine Empire. As a result, the then Patriarch of Constantinople summoned a Synod in Constantinople in 843. This Synod resulted in the issue of a number of anathemas against iconoclasts. These anathemas are proclaimed each year at all Eastern Orthodox parishes in the world during the first Sunday of Great Lent, known as the Sunday of Orthodoxy:
To those who scorn the venerable and holy ecumenical Councils, and who despise even more their dogmatic and canonical traditions; and to those who say that all things were not perfectly defined and delivered by the councils, but that they left the greater part mysterious, unclear, and untaught, ANATHEMA.
To those who hold in contempt the sacred and divine canons of our blessed fathers, which, by sustaining the holy Church of God and adorning the whole Christian Church, guide to divine reverence, ANATHEMA.
To all things innovated and enacted contrary to the Church tradition, teaching, and institution of the holy and ever-memorable fathers, or to anything hence-forth so enacted, ANATHEMA.
To those who accept the visions of the prophets, albeit unwillingly, and who do not – O wonder! – accept the images seen by the prophets even before the incarnation of the Word, but who babble that the intangible and invisible essence was seen by the prophets, and who, even when they concede that images and types and forms were truly revealed to the prophets, still cannot endure to depict in icons the Word become man and His sufferings for our sake, ANATHEMA.
To those who hear the Lord’s words: “Had ye believed Moses, ye would have believed Me” and so forth, and who understand Moses when he says, “The Lord our God will raise up to you a prophet of your brethren, like me,” and who then say that they accept the Prophet, yet they do not permit the grace and universal salvation of the Prophet to be depicted in icons, how He was seen, how He lived with mankind, how He worked healings of incurable passions and diseases, how He was crucified, was buried, and arose, in short, all that He both suffered and wrought for us; to those, therefore, who cannot endure to gaze upon these universal and saving deeds in icons, neither honor nor worship them, ANATHEMA.
To those who persist in the heresy of denying icons, or rather the apostasy of denying Christ, and who are not counseled by the Mosaic law to be led to their salvation, nor convinced to return to piety by the apostolic teachings, nor induced by patristic exhortations and explanations to abandon their deception, nor persuaded by the agreement of the Churches of God throughout the whole world, but who have once and for all joined themselves to the portion of the Jews and Greeks: for the blasphemies cast by the Jews and Greeks at the prototype, have been shamelessly used by the former to insult through His icon Him that is depicted therein; therefore, to those who are incorrigibly possessed by this deception and have their ears covered towards every divine word and spiritual teaching, since they are already putrefied members, having cut themselves off from the common body of the Church, ANATHEMA.
To those who do not confess that the Word and Son of God was begotten without change from the Father before the ages, and that in these latter times, out of His abundant loving kindness, He was incarnate of the immaculate Theotokos Mary and became man for our salvation, taking upon Himself all that pertains to us save sin; and to those who do not partake of His holy and immortal Mysteries with fear, since they consider them to be mere bread and common wine rather than the very flesh of the Master and His holy and precious blood shed for the life of the world; to such men be, ANATHEMA.
To those who do not worship the Cross of our Lord and God and Savior Jesus Christ as the salvation and glory of the whole world, as that which annulled and utterly destroyed the machinations and weapons of the enemy and redeemed creation from the idols and manifested victory to the world, but who consider the Cross to be a tyrannical weapon; to such men be, ANATHEMA.
To those who attack the Church of Christ by teaching that Christ’s Church is divided into so‑called “branches” which differ in doctrine and way of life, or that the Church does not exist visibly, but will be formed in the future when all “branches” or sects or denominations, and even religions will be united into one body; and who do not distinguish the priesthood and mysteries of the Church from those of the heretics, but say that the baptism and Eucharist of heretics is effectual for salvation; therefore, to those who knowingly have communion with these aforementioned heretics or who advocate, disseminate, or defend their new heresy of Ecumenism under the pretext of brotherly love or the supposed unification of separated Christians, ANATHEMA.
1. Galatians 3:23
2. 1 Timothy 6:16
3. Isaiah 40:18
4. On the Holy Icons (tr. from Greek, St. Vladimir's Seminary Press,1981), p.24
5. Ibid., p.25