Also human race has committed atrocities against the environment since our earliest days.

Back in prehistoric times hunter parties used to create wildfires to hunt animals, completely disregarding the environmental damage of burning great amount of lands.

I think it’s disingenuous to talk as though you need 5 billion people to start impacting the land. One household destroys plenty. The majority of North American land was being cultivated in some fashion at the time of Spanish discovery, and the population of the continent was probably around 3 million people, 5% of modern day.

This study is about the Neolithic era, which is a period of huge earthworks. You may have heard of some of them. The idea that they were rotating crops to manage soil chemistry and practicing agroforestry 4-6000 years ago in a society known specifically for making giant fucking tombs is pretty neat when today with all the progress we’ve made we’re clear cutting the Amazon rainforest for cattle and similarly out of place monocrops.

Crops started failing right before The Black Death because people still didn't know about fertilizers and farming simply depleted the soil. If not for the plague Europe would see famine because its farming was... unsustainable.

The land use practiced by neolithic people is for example https://en.wikipedia.org/wiki/Dehesa Those ecosystem exist since thousands of years because they are.... sustainable.

Probably not incidental, if the population was sedentary they would probably burn through the trees faster then they would naturally grow back.

Humans, especially in northern latitudes, burn through wood pretty quickly for cooking and warmth.