Why have not all apes become humans?

I read your paper on the Future of Homo Sapiens. Fascinating read! I have one question though - you'll probably find it really simplistic but here goes ....If humans evolved from apes then how come all apes have not evolved into humans by now?

It is not improbable that humanoids have developed more than once. But humans are not nice to competiting species. Look at how the Native Americans or the Australian Aborigines were treated. Quite probably, one humanoid species eradicated all competing species.

The Neanderthals and Homo Sapiens lived together for thousands of years, but finally the Neanderthals disappeared. Experts do not agree on why, some claim that Homo Sapiens eradicated its competitor, while others believe that climate changes causes the Neanderthals to disappear.