> The earth is old, and so is the universe.
Sincere question for you. Before the curse, there was no death, and I’d conclude also no physical decay of any kind. The creation was perfect. So, how do you see behind that event? I’d posit that there was no decay of any kind before sin and the consequent curse on all creation. Creation went from perfection without decay, to something ridden with entropy, decay and death.
Also, before the Seven Day Creation, we had a different “aeon”—Age; Peter's “First Earth Age” and "First Heaven Age", which KJV just translates "First Earth" and "First Heaven".
It was different in many respects from this, the “Second Earth Age” and "Second Heaven Age"; and the details of the differences do not particularly concern us, as far as God is concerned. If it did, He would have explicitly told us more about it.
What we do see is that that Age was ended by Satan's Rebellion and Overthrow, so we have enough to tell us why, though not when.
It is enough to put us on track in this Age, to help make the choice for God or Satan, before the coming of the Third Aeon—the Restored Earth & "Third Heaven Age"... without the presence of Satan & those who choose badly.
It is a bit of a shame that KJV translators used ‘earth’ and ‘Heaven’ as the translation of ‘aeon’, but they did...just like in ONE spot (Acts 12:4) they translated ‘Pascha’ as ‘Easter’ instead of ‘Passover’, like all the other places it occurred.
So sharks ate salads?
God's creation is perfect. However, you cannot logically leap from the fact that is perfect to the conclusion that there was no death or physical decay.
Read the creation account again. Eden was a special place, different from the rest of the earth.