they also haven't been existing in some sort of isolated preservation environment and instead have lived alongside horticultural* and agricultural societies with varying degrees of contact and conflict. They can even be offshoots of those civilizations who simply started surviving on the margins as they could.

In the Dawn of Everything, Graeber points out that until agrarian cultures moved in, "nomadic hunter gatherers" would have lived next to rivers, prime real estate. The current populations have spent literally ten thousand years being pushed off such lands. Even assuming that current peoples were a "preserved window into the past", which seems unlikely to begin with, such people living far away from ideal farmland would have been a minority of "nomadic hunter gatherers" even at a time when that was the majority of humans.

To say nothing of cultural and physical exchange of people (like... People would flow in and out of these communities, often voluntarily)