
This is possible, the idea is quite interested but it's not already proved - another human species would have some distinct genetic characteristics genetic not only different height and eyes. The imune system would be a little different, the metabolism would also be different - not much, just a different food digestion. It's like comparing lions and tigers.
The main conclusion is that we are still humans no matter the differences, even the lion and tigers can have puppets together and they are all feline.