The Gospels are very clear when and where and how Jesus originated. He cannot have been there in the beginning unless some serious reading-in is done with the scriptures and a dismissal of other scripture that shows Jesus to be exclusively human.
In the complete absence of any mention of an "Eternal Son, eternally begotten, or other such ideas, Jesus must be accepted as revealed. A man like us in every respect (Heb 2) who was tempted, died and was raised back to life by his Father and God, brought into the heavenly realm and now sits by the side of God (John 20:17, Acts 7:55, Mark 16:9).
From Col 1:15-
- The Son is the image of the invisible God - this doesn't make him God. An image of something is a representation only. We are also an image of God in Christ Rom 8:29. (Mark 12:16 the coin is an image, just as Jesus is)
- the firstborn over all creation. The only way this aligns perfectly with the Gospels is for this to apply to the same instance of "firstborn from among the dead" which happened at his resurrection to spirit, immortal life that he never had before. 1Pet 3:18, Rom 6:9
- For IN him all things were created. Not by, IN. Clearly the context, as you have noted, is of the new age beginning with the giving of the holy spirit to enable the new church - the spiritual body of Christ.
- things in heaven and on earth, Note that 'things IN heaven and ON earth' are not referring to a Genesis creation either. God made THE heavens and the earth, but all things come to their full potential only in Jesus.
Yes, a pre-existing Jesus is not a biblical idea - there is only suppositional and inferred support that creates conflicts with a lot of scripture.
While there are many scholars who imagine and declare a lot of things, they must be held to account if the bible is regarded as the primary source of truth. Jesus is only pre-existing in the mind and plan of God - what God plans always comes to pass. Not because time has allowed it to be, but because time has eventually revealed what was declared because God said it was or would be.
Does Colossians 1:15, refer to the Genesis creation? No. It may only be understood that way if taken out of context and read in isolation.
Is Jesus 'merely' presented as the firstborn from the dead? It's hardly 'merely'! Jesus as the glorious obedient and faithful son of God fulfilled every requirement as the 'last Adam' and qualified to become heir to all God's creation Heb 1.
To say that Jesus is NOT the first-'born from the dead' is to misunderstand 'dead' and 'born'. Dead refers not to the lack of physical life, but the complete lack of life potential. That's why Jesus refers to physical death as 'sleep'. All CAN be raised to new life if they have lived in this age.
Our friend Lazarus has fallen asleep; but I am going there to wake him up. John 11:11
We shall not all sleep, but we shall all be changed ...and the dead will be raised incorruptible 1Cor 15:50-53.
'Dead' also refers to the general state of man who must die due to sin's penalty. These are the dead, from which Christ rose on all men's behalf thereby enabling a life after death for all who will accept his offer made possible by his sacrifice - in this age or the next.
Jesus is indeed the firstborn from the dead - the dead due to sin, from which no man can arise to take up the eternal life God intends all receive - IF they accept the terms offered!
One can be 'raised from death/sleep' only by God and His exalted son. The resurrection reveals that all will rise to a judgement (except those in Christ who will be raised to life eternal, as Jesus was) and they will still be physical - able to die in the second death Rev20. When a believer is risen to spirit life, they are 'born from above' and granted eternal life. That's why Paul teaches that flesh and blood cannot enter the kingdom 1Cor 15:50.
...that having been born of the Spirit is spirit John 3:5
Jesus is the first to be 'born from above' - being given spirit life - as the Father has, He gave to Jesus. Jesus IS spirit now, but he was not when he died (else how could he die?). John 5:26 Only God has immortality - Jesus did not. Now, after being raised by God and exalted to God's side, Jesus too has immortality.