Tree's have various life spans too.
I think mostly what the OP is thinking of are Redwoods, Giant sequoia, certain kinds of pines like Limber Pine. They can get up to the 3,000 to 4,000
Some species of Oak can get up to 1,500 years.
I have Red Oak here on my land, and they can get up to 500 years, but most die after 200 years. White oak that is here can get up to 300, Water Oak up
to 175. But that's the longest they can get to. Disease, drought, fires (natural ones) storms, can cut their lives short.
Longleaf pines that grow here (they get pretty darn tall) can live up to 300 years......but not a lot do. Fires, and storms take a lot of them out.
I've watched these trees bend over more than 50 degrees in a storm, and then CRACK, that's all she wrote for them.
Thing is: these pines are like weeds! They'll start growing enmass and quickly too.
We have wild cherry, hickory, persimmons (they only live 60 years), and a huge mixture of other trees here in the SE too.
But rest assure, forests are here.
Here's my back yard:
Plenty of places that I go, there are lots of old growth forest abound:
Burell's Ford, SC
Mistletoe State Park, GA
Huntington Island, SC
Wild Turkey Federation, SC
And while yes, us humans do intrude, we also can live with the old trees.
This is South Boundry Road here in the city I live in. These oaks are up to 200 years old: