Probably billions of years old. There really isnt any evidence of an actual age and i dont think it's really worth having a position on. I read an article last year that traced back human DNA to something around 120,000 years ago that all people on earth can be traced back to which was pretty interesting. Dont quote me on this but i think it suggested that all humans have a common link to a female from northern africa that lived around 120,000 years ago. It was similar to how all dog breeds have a common ancestor from northern Asia or Europe that was domesticated around 20,000 years ago.
It sounds kind of crazy but probably isnt any less crazy than the idea of evolution happening all over the world independently at the same time 10,000 years ago leading to the same species, just with different pigmentation in their skin.