In a wonderful article (paywalled) in The Australian, Greg Sheridan starts with:
The first Christmas Day was the moment when eternity announced its
presence in time. The immense and the everlasting pierced the thin veil
An interesting aspect of the creation account: Genesis 1 is that it does the very some thing. One of the challenges in many 'religions' and indeed aspects of philosophy, is the conjoint function of 'eternity' and 'time' or universals and particulars.
Some religious views deal with this by placing veils of illusion between what is foundationally real and the human experience; not Christianity (or Judaism, for that matter).
God shows his congress with us in time by acting in the constrained time that we live in: he created in six days: he paced his interaction with us in terms of our limits. There was nothing made up or artificial in this. There are, after all, no limits to the creator.
Genesis 1, along with the incarnation, shows the creator as real in the contingent creation. It also shows that our experience of life and God is equally real. Not illusion, not imaginary, not a dream. Real.