Why do apes still exist? If we are evolved from apes, why don't all ape evolve and become human. Or > Why the today's ape stop evolving to become a human?

I am not going to bother putting any references for this answer as all the information is a google search away.

**Humans did not evolve from apes.** Extant humans and apes developed from a common ancestor. One lineage from this common ancestor evolved and became apes. Another lineage went on to become humans.

Some study material here and here.