there is no question that the universe was created billions of years ago
there is no question to you
that this is one of the fundamental tenets of astronomy; studying it without this assumption is foolish.
yes i agree it is an assumption. and the whole rest of astronomy is based on this ASSUMPTION. there is also of course the second assumption: that there is not a creator.
Chazal knew what was known in their time , but not more. This should be obvious.
it is not at all obvious to me. im glad though that the minds, Nevius, and capabilities of Chazal are obvious to you.