At this time of year, it is natural for me to think about the birth of Jesus; and that leads back to Jesus before he was born, in his pre-mortal spirit life.
As I understand things; Jesus was the only pre-mortal Man who was wholly-aligned with the will of God. Why this should be, I don't know - and it may not have an explanation. The idea is that Jesus was (in some sense, presumably including - but not confined to - the literal) the first-born of the children of God; but that in itself does not tell us why he was unique.
What is it that makes a person's will aligned with that of God? The answer is love - so we can infer that Jesus loved God such that there was an absolute harmony between them - and that no other pre-mortal Man did so; and no other could be Saviour.
Hence Jesus, and only Jesus, was co-creator of this world (as described in the early verses of the Fourth Gospel). Co-creation is only possible when love ensures a harmony; only in that way may two or many parties may contribute to a single (harmonious) creation - genuine independence of self-creation is made compatible with the coherence of all that which is created.
(Sin is lack of love, lack of alignment; such that this harmony is prevented; sin is also the state of labile mortality - and full co-creation is only possible between immortal persons, whose love is everlasting - not mortal.)
The Messiah was both co-creator, and future Saviour - by 'saviour' was meant that he was the only means by which other Men could attain to resurrected everlasting life; and full divinity.
Yet, although co-creator, the pre-mortal Jesus was nonetheless in a vital sense incomplete because immature - he lacked that final development which was provided by his incarnation, death and resurrection; and only after this completion could Jesus ascend to Heaven and take up full divinity.
When Jesus was born, this was his history. At birth and for (apparently) thirty years, Jesus was unique in his love of God, but otherwise an ordinary Man - except for his covert destiny. It was only after the baptism by John that the incarnated Jesus assumed divine power - fully divine in power but a mortal Man.
At this point, I think Jesus had done his work of salvation for Men - as evidenced by the resurrection of Lazarus. And the completion of Jesus's development - to immortality and full divinity - was attained via his own death and resurrection.
Thus Jesus became as his Father; a full creator, capable of making worlds and procreating spirit children.
Note: For simplicity, above I have left-out the role of celestial marriage and the dyadic love between man and woman which was the basis of the creation by our Heavenly Parents (i.e. God); and that the resurrected Jesus would likewise marry an eternal resurrected woman in order to attain full creative divinity - the first stage being enacted during his mortality, with Mary Magdalene (of Bethany) as described in the Fourth Gospel.