>>213097995They did disappear. As separate species.
We might have some of their dna mixed in ours but it's not much in total.
All that's left are some crumbs.
Because if lets say Sapiens and Neanderthals completely merged together into one species, then we wouldn't be Homo Sapiens. We'd be a hybrid mix with half our dna being Neanderthal (give or take).
But we're not.
It's like having Rottweilers go extinct but saying they still exist because you have a Mastiff with 3% Rottie dna mixed in..