I have never been able to make coherent sense of the standard explanations for the nature of Jesus Christ.
This, of course, does not matter when it comes to being a Christian - we simply need to acknowledge that Jesus was who he said he was (eternal Son of God, Son of Man), and to love him, have faith in him...
Christians, as such, don't need to assert the exclusive validity of any specific theory of why-and-how that situation arose.
Nonetheless, it is natural enough to seek an answer to questions about how and why Jesus got to be what he was, what was the 'mechanism' by which his unique status came-about: how it was that Jesus lived, died - like other men - but also, uniquely, brought us resurrection and life everlasting.
Anyway, an answer to this came to me yesterday that Jesus Just Was. That there is no causal expanation for why Jesus was who he was; but that he Just Was who he was.
The background is that all Men are unique, and various; so we become God's children as already-unique and we are incarnated as already-unique; and we end-up as unique resurrected Beings. And that Jesus was able to be our Saviour simply because he is, was, always had-been just that.
Not as 'part of a plan' from eternity; but an an unique person who enabled this unique possibility; which would otherwise have been impossible.
Somehow this insight seemed to quell the doubts, answer the nagging questions... Jesus Just Was. He was uniquely capable.
Of course, Jesus then had-to choose to, agree to become our Saviour - and he did, for which our gratutude and love are due.