The creation of a new form from an existing one does not necessitate the elimination of the older form.
The question itself is based upon a flawed premise based upon a misunderstanding of evolution. There is no natural tendency for a chimpanzee to become more like a human, or for things to get unambiguously improved over time. Yet this is a very seductive misconception.
I refer you to the answer I gave some moments ago.
(But if you can't find it, it was because intelligence was involved.)
ML/NJ