most of the established timelines are based on "well this is the oldest thing we've found so far". most of it is probably wrong

There are other hominids apart from homo sapiens during those periods. These will probably be Denisovans

No, it's known that Homo Erectus left Africa and colonised Eurasia up to East Asia a bit more than 2 million years ago.

The estimate on when "we" left Africa often means modern humans, Homo Sapiens.