The New Testament is trying to make sense of Jesus, and all would-be Christians need to do the same.
First, they need to understand why God the prime creator could not do what Jesus did -- why Jesus was necessary.
But immediately this raises the question of what Jesus did. What aspect of Jesus is central?
This took me a good while to settle to my satisfaction, indeed it is only in the past year or so that I have, from reading the Fourth Gospel 'in isolation '.
This clarified that the main thing Jesus did was to be resurrected to eternal life in Heaven. Jesus was necessary because God the creator could not do this.
And because Jesus was divine before he did this,we can, if we love and trust him, follow Jesus through our own deaths into resurrected eternal life.
There are many other different, and indeed contradicting, theories of what Jesus did and why he was necessary, in other parts of the Gospels and Epistles, and in different past and present denominations; but I regard the Fourth Gospel as the real and true explanation.
Yet it seems by far the least known, least considered of canonical Biblical explanations; which I can only regard as a major historical tragedy.
Note. This was brought to mind by CS Lewis discussing Jesus in terms of the myth of a dying god, a sacrificed god. But that is Not the myth. Jesus was not a sacrifice, nor did he stay dead. Jesus was not a propitiation, because the creator does not want to be propitiated, nor need it. Jesus's life was a positive gift to all the children of God - his brothers and sisters; an offer of Heavenly eternal life which we may accept or reject.