Exactly. Going back to hunter-gatherer and living off the land like that is hardly sustainable with the current population: Earth has 5.7e7 sq mi surface, but 7e9 people, i.e. 8.1e-3 sq mi/person. Hunter/gathers seem to need (after a short google session) need around 1e-2 (Tropical) to 1e2 sq mi (Savannah) per person.
This might be more accessible if you weren't using scientific notation. They aren't exactly astronomical numbers