People can, and do, live in some really hostile places.
It would be possible to live up mountains or in the most dense forests for example. It all comes down to personal choice. Personally I wouldn't like to live in the countryside let alone in the jungle but some people do and like it. What I can tell you is the amount of land there is on the surface of the Earth. Land accounts for 148,000,000 square kilometres or 57,000,000 square miles.