"If I descended from an ape, how come apes are still here?"

I'm no RAZD, but how about looking at the range of variation in cranial capacity as an example?
The image below plots the cranial capacity of all fossil Hominins and compares them to the range of variation in cranial capacity of modern humans, as shown on the far left. Also shown is variation in cranial capacity of modern Chimpanzees, and as you can see the further back you go the cranial capacity of these fossils tend towards the range seen in chimps. Source including references