For me, this, here, now, is New Year - in the sense that a year is an astronomical division of time, and 23-24 December would have been the first time that our ancestors could have been sure that the shortest day (the winter solstice) had come and gone; and the New Year had begun.
I think this accounts for the (approximate) date of Christmas: 1. Wait until the solstice has been and gone and the New Year has begun; 2. Spend a day or two preparing a feast; 3. Have the feast. Hence the feast of the New Year, to celebrate being in the New Year, comes after the event of the solstice.
The connection with a celebration of Jesus's birth is obvious enough, when we think of the analogy between the New Year and the New Era in the history of creation: creation inflects at the life of Jesus. But at what point of the life?
What is born, what begins, with the New Year is the potential, not the actuality. The destined, but not actual, Messiah was born.
The actuality was the Baptism of Jesus: that was when Jesus attained his full divinity and the gifts of divinity (to do miracles, especially to raise Lazarus); but at first he was a 'temporary' and 'local' deity in a mortal body that was doomed to die; and Jesus needed to die and be resurrected before he could attain to permanent full divinity - and with the universal scope of the Holy Ghost.
Probably therefore, if we want to mark the major events of Jesus's life with feasts; the Baptism of Jesus ought to be the major feast, rather than a minor and rather obscure celebration.
The birth, death and resurrection, ascension and return of Jesus as the Holy Ghost are all vital - but perhaps the Baptism of Jesus, when Jesus was recognised as the Messiah and when the divine spirit descended upon him and stayed with him... well, that was the defining point in the history of the universe! It was the exact point that death was defeated and eternal life became possible (with Lazarus as the first recipient).
But then, Christians have misunderstood the significance of Jesus's baptism since whenever they decided not to take seriously, and thereby accord priority to, the Fourth Gospel.
Anyway, today is the New Year and the birth of the Messiah - who turned-out to bring something so very different from what was expected; and so different from what has since so often been projected upon him.
Luckily for us, we don't need to know much, or do complicated stuff, to benefit from the gift Jesus brought; simply believe him, and follow him - both of which can be summarised as love him.
Love Jesus as we should love our family, as a solid background fact of life; because his gift is precisely to allow us (if we want) to join his family, eternally, as gods - participating in the everlasting work of creation.