“Did the first trees have rings in them?”
Depends. Were they planted on the third day and grown naturally thereafter, or were they created fully grown? I think the oldest known individual (non-clonal) tree isn’t more than 5k years old, so there’s really no problem either way.
And remember, why on earth do we need to think that briyas haolam happened in the context of what we consider is a day. There wasn’t even a sun or moon til the fourth day- there’s no actual day.
And considering that there’s a passuk or chazal that every day for Hashem is a thousand years, we really don’t need to be tied down to 6000 years, do we?
Also my AP Bio class has a theory about the chicken and the egg. Evolutionarily speaking (which is how you have to think in AP Bio, for those at risk of being offended), the egg has to come first, as whatever creature evolved into the common chicken probably laid eggs, considering that other species also lay eggs.