Did the Holy Spirit manifest in people before Jesus?
The answer is YES.
The Holy Spirit was first described in Genesis1:2.
And the earth was void and empty, and darkness was upon the face of the deep; and the spirit of God moved over the waters.
I've seen answers on this site that interpreted this passage or associated this passage to "Mystery of Incarnation". The Holy Spirit hovers, moved or overshadowed the "waters". What "waters", are we referring to? The water in the womb of Mary, that the Holy Spirit sanctified to form the Logos. After Genesis1:2 or the Logos was formed mystically in the waters in the womb, only then, God can say, "Let there be Light" in Genesis1:3.
And the next passage that the Holy Spirit can be seen was, when God breath into Adam nostrils the Holy Spirit...in Genesis2:7
And the Lord God formed man of the slime of the earth: and breathed into his face the breath of life, and man became a living soul.
The Holy Spirit is the giver of life, the breath of God.
This is why Jesus and the Father are One and both God, because from their breath, they breathed out the Holy Spirit to give and restored divine life in a soul.
The OP cited passages in John's gospel..
In John 16:7-8, Jesus says:
“But I tell you the truth: it is to your advantage that I am leaving; for if I do not leave, the Helper will not come to you; but if I go, I will send Him to you. And He, when He comes, will convict the world regarding sin, and righteousness, and judgment” (NASB2020)
Jesus did not explicitly said, the "Holy Spirit" but stated the word "Helper". The word "Helper" was also attributed to Eve. In Catholicism, Jesus is the New Adam, and Mary is the New Eve.
How can we reconcile this teaching from the gospel of John?
Jesus came into this world in a form of a slave, Jesus was fully man and fully God, and His divinity seems stripped, as St.Paul described it..
Who, existing in the form of God, did not consider equality with God something to be grasped, 7but emptied Himself, taking the form of a servant, being made in human likeness. 8And being found in appearance as a man, He humbled Himself and became obedient to death—even death on a cross. -Philippians2:6-8
How to ponder this profound mystery?
We must look at Jesus, not yet anointed by the Holy Spirit from birth up to thirty (30) years old. And the "anointing" only came at Baptism in the Jordan River, where God the Father was seen and the "Holy Spirit" descended on Jesus, and Jesus became the "Advocate or Helper" of all the Apostles.
How about the "another Advocate" or the "Helper" that Jesus was promising the Apostles that He will send by asking the Father? The "Helper" is not a Spirit but a person too like Jesus. And this will lead us in the Upper Room, the Descent of the Holy Spirit.
In the Upper Room, who among the Apostles can be anointed as the "Helper or another Advocate"? Remember, the Holy Spirit cannot reside in a heart tainted by sin, as King David pleaded God to "create in him a clean heart", in order for the Holy Spirit to abide in him.
We can see that the Apostles must prepare their hearts and minds to receive the Holy Spirit, and so, none of them are worthy to fulfill the role of "Helper or another Advocate". It was the the Theotokos who teach and guided the Apostles how to receive the Holy Spirit, that overshadowed Her.
To recap, the Holy Spirit was breath in to Adam, How about Eve? Adam as an anointed High Priest or Bishop can anoint Eve to become his "helper or a deacon" in the garden of Eden which is a temple of God. https://www.catholicnewsagency.com/resource/55702/adam-high-priest-of-humanity
Jesus on the other hand, was anointed when the Holy Spirit descended on Him, it was not breath in by the Abba Father, but it's more than overshadowing, it is an indwelling, to empower Jesus in His redemptive mission.
In the Upper Room, the Holy Spirit descended to all the Apostles, but since their hearts was not yet fully form or cleanse to allow the Holy Spirit to dwell perfectly and completely, they are not yet prepare to fulfill the role of Jesus, the Advocate, and so, the "another Advocate" will not come from the Apostles, but from the chosen Woman whom the Holy Spirit already overshadowed, but not yet fully, perfectly and mystically indwelt at that time, but at the Foot of the Cross, something happen, the Seven Sorrows that the Blessed Virgin Mary embraced had prepare or hewn Her Immaculate Heart to allow the Holy Spirit to dwell in Her perfectly, completely and mystically.
In closing the Holy Spirit indwelt the Theotokos, Her Sorrowful and Immaculate Heart became the "perfect dwelling place for the Holy Spirit". and this can be seen in Proverbs9:1 and Sirach24:12. And the Holy Spirit dwelling in Theotokos is a teaching of the Catholic Church, see Catechism.
CCC721 Mary, the all-holy ever-virgin Mother of God, is the masterwork of the mission of the Son and the Spirit in the fullness of time. For the first time in the plan of salvation and because his Spirit had prepared her, the Father found the dwelling place where his Son and his Spirit could dwell among men. In this sense the Church's Tradition has often read the most beautiful texts on wisdom in relation to Mary.101 Mary is acclaimed and represented in the liturgy as the "Seat of Wisdom."
In her, the "wonders of God" that the Spirit was to fulfill in Christ and the Church began to be manifested:
So, when we say Mary is the "Seat of Wisdom", and the Holy Spirit is the Spirit of Wisdom that was qanah or birthed in Proverbs8:22, it means the Spirit of Wisdom that anointed all Old Testament elect, like King Solomon, is the same Spirit that anointed Jesus as Christ in the Baptism at Jordan River, and Jesus became the Advocate, and the same Spirit of Wisdom descended in the Upper Room, that anointed the Blessed Virgin Mary to fulfill the role of "Helper or another Advocate". In the words of one of the Great Marian Saints, a Doctor of the Church, named St.Alphonsus Liguori...
"In His eagerness to show you mercy, God send Jesus the Advocate, and to increase your confidence even more, He sent an another Advocate....
...go to Mary and you will find salvation."
Mary is the "Helper" or the "Another Advocate", because like Jesus Christ in the Baptism at Jordan River, received the anointing upon the Descent of the Holy Spirit, it is the same in the Upper Room, when the Holy Spirit descended fully, perfectly and mystically to the hewn heart of the Blessed Virgin Mary.
"Wisdom has built her house, She has hewn out her seven pillars."-Proverbs9:1
While St.Augustine said, "Man is restless until it rest in Thee.", the Almighty God, the Spirit of God was also "restless" in the Old Testament, because She cannot find a perfect dwelling place, and so the Holy Spirit "carved or hewn" a perfect dwelling place for Her, by carving the Seven Pillars of the Seven Sorrows, and finally the Spirit of God, the Spirit of created Wisdom, can now finally rest...
"Then the creator of all things commanded, and said to me: and he that made me, rested in my tabernacle."-Sirach24:12
In closing, Veni Creator Spiritus now rested in a Tabernacle or in the Sorrowful and Immaculate Heart of Mary, the Seat of Wisdom.
Mary Seat of Wisdom, grant us wisdom and pray for us.
Sweet heart of Mary be my salvation.
To entertain your confusion about "quad", it would seem to appear that the Spirit of Wisdom that was "qanah, birthed or created" must be seen in the contemplative reflection of St.Maximillian Kolbe in a much more mysterious words "quasi-incarnation", but this topic is too broad to include in my answer.