What is the best way to increase the natural habitat same as back in old days?

Well, let's see what you think.

Human or animal habitat? How "old" are the days?

More deer exist today than did 100 or even 200 years ago... so you need a lot more specifics before you can even begin to arrive at a factual answer.

Human birth control. Human epidemics. Humans hop on space ship and don't come back.

Humans are incapable of natural habitat.