Introduction: Let’s start with a brief overview to establish who’s who from the LDS point of view:
Latter-day Saints commonly refer to God the Eternal Father as Elohim, a Hebrew plural meaning God or gods, and to his Son Jesus Christ, as Jehovah.
The first spirit son of Elohim (Heavenly Father) and his wife (Heavenly Mother) is called Jehovah.
Jehovah came to earth as Jesus to be born as a man in order to progress to godhood (exaltation).
To members of the Church of Jesus Christ of latter-day Saints there is no one else higher then Heavenly Father (Elohim).
God the Father is the Supreme Being. He is the ultimate Creator, Ruler, and Preserver of all things.
He is the God over all creation as Latter Day Saints know it. Take note of that statement. Hebrews 1:2 is used as evidence that there are many worlds. Elohim is God over this world.
Father in Heaven: The Father of the spirits of all mankind. Jesus is his Only Begotten Son in the flesh. Man has been commanded to obey and give reverence to the Father and to pray to him in Jesus’ name.
God the Son: The God known as Jehovah is the Son, Jesus Christ… he is the eldest of the spirit children of Elohim... it was actually Jesus who was the Creator under the direction of God the Father [Elohim].
Jesus Christ: https://www.lds.org/scriptures/gs/jesus-christ?lang=eng
Brief overview of LDS theology with regard to God the Father, Jesus Christ, the Son of God and the Eternal Father: About 124 B.C. the book of Mosiah (in the Book of Mormon) made these prophesies:
For behold, the time cometh, and is not far distant, that with power, the Lord Omnipotent who reigneth, who was, and is from all eternity to all eternity, shall come down from heaven among the children of men... And he shall be called Jesus Christ, the Son of God, the Father of heaven and earth, the Creator of all things from the beginning; and his mother shall be called Mary. (Mosiah 3:5 and 8)
Note that it is “the Lord Omnipotent” who is to come down from heaven to be called Jesus Christ. He is “the Son of God, the Father of heaven and earth, the Creator of all things from the beginning.” Mosiah chapter 15 goes on to say Father and Son are one God, the Eternal Father:
God himself shall come down among the children of men, and shall redeem his people. And because he dwelleth in flesh he shall be called the Son of God, and having subjected the flesh to the will of the Father, being the Father and the Son - the Father, because he was conceived by the power of God; and the Son, because of the flesh; thus becoming the Father and Son - And they are one God, yea, the very Eternal Father of heaven and of earth (Mosiah 15:1-4).
God the Eternal Father was once a mortal man who passed through a school of earth life similar to that through which we are now passing (The Gospel Through the Ages, 1945, p 104).
I am going to tell you how God came to be God. We have imagined and supposed that God was God from all eternity. I will refute that idea, and take away the veil, so that you may see. … It is the first principle of the Gospel to know for a certainty the character of God and to know...that he was once a man like us.... (“King Follett Discourse,” Journal of Discourses 6:3-4, also in Teachings of the Prophet Joseph Smith, 345-346, and History of the Church, vol. 6, 305-307) http://mit.irr.org/god-was-once-man-us-finessing-off-putting-mormon-doctrine
In the Bible Jesus says God is Spirit, and his worshippers must worship in spirit and in truth (John 4:24). However, Joseph Smith saw fit to change these words to deny that God (read Elohim) is Spirit:
Is God a spirit? John 2–4: “Ye Must Be Born Again” John 4:24: Some may be confused by Jesus’s statement that God is a spirit. The Joseph Smith Translation of this verse provides an important clarification: “For unto such hath God promised his Spirit” (in John 4:24, footnote a). Modern revelation also teaches that God has a body of flesh and bones (see D&C 130:22–23; see also Genesis 5:1–3; Hebrews 1:1–3).  https://www.churchofjesuschrist.org/study/manual/come-follow-me-for-individuals-and-families-new-testament-2019/07.scripture_title4-p11#scripture_title4
The manifestation of God's physical body came in a revelation to Joseph Smith in 1843:
The Father has a body of flesh and bones as tangible as man’s; the Son also; but the Holy Ghost has not a body of flesh and bones, but is a personage of Spirit. Were it not so, the Holy Ghost could not dwell in us. https://www.churchofjesuschrist.org/study/scriptures/dc-testament/dc/130.22?lang=eng#21
The Bible says that God is from everlasting to everlasting (Psalm 90:2) and that He is eternal (1 Timothy 1:17). He is the Alpha and the Omega, the First and the Last, the beginning and the end (Revelation 1:8; 21:6; 22:13). God the creator was not himself created. But the Book of Mormon says God was once a man and has a body of flesh and bones. Mormons worship Elohim, God the Father, through Jesus, God the Son. They are God the Eternal Father. What is unclear is who created the man who became God the Eternal Father. What is also unclear is whether Joseph Smith understood the difference in meaning between eternal and immortal. After all, how could a created being be eternal? Here is the LDS definition of ‘eternal life’ and ‘immortality’:
Eternal life is the phrase used in scripture to define the quality of life that our Eternal Father lives. The Lord declared, “This is my work and my glory—to bring to pass the immortality and eternal life of man” (Moses 1:39). Immortality is to live forever as a resurrected being. Source: https://www.churchofjesuschrist.org/study/manual/gospel-topics/eternal-life?lang=eng
Conclusion: One possible LDS justification or explanation for their belief that Elohim, the Supreme Being, also known as God the Eternal Father, or God the Father, or Heavenly Father, and who has a body of flesh and bones, is that Joseph Smith was the recipient of modern revelation 
Another is that the Book of Mormon trumps The Bible. 
Articles of Faith – 8: We believe the Bible to be the word of God as far as it is translated correctly; we also believe the Book of Mormon to be the word of God.  http://lds.org/scriptures/pgp?lang=eng
Disclaimer: In the Bible God the Father was never created, is not a man and He is not God the Son. And Jesus, the Son of God, is not Jehovah, nor is he God the Father. That’s what my Bible says, and I believe the Bible. If I have misrepresented the beliefs of the Church of Jesus Christ of Latter Day Saints I would appreciate an explanation of where I have gone wrong.