In fact, Hashem created a completed mature world 6000 years ago which quite probably was millions of years old. Hashem didn’t create Adom as a baby or the trees as saplings but He created them complete and fully mature. So too the earth. We don’t know the intricacies of maise b’reishis. There are numerous questions when learning parshas b’reshis and the chachomim have advised us to just move on.
While chazal were b’keyim in Astronomy, it was from the perspective of an earthling and not from the perspective of telescopes in space.
And no matter how much you jump up and down and deny it, in gemara Sanhedren, which we in daf yomi just completed and in other places, it’s apparent that chazal were not privy to certain facts concerning the sun’s movement around the earth.