To answer the question "why aren't apes evolving into humans?" is simple. Biology rests on diversity. Things have to evolve in different ways or else the ecosystem crumbles. If every organism on earth was a human, we'd have to resort to cannibalism and eventually we would all die without plant life to bring in energy from the sun. Humans aren't "better" than apes, we're just different. We evolved different features because of specific circumstances our ancestors had to endure, and because certain beneficial random mutations happened that were different from apes. We evolved to fit a different niche in the environment. For some reason, apes tended to survive more in their environment when they walk on four legs and have fur, or they simply didn't evolve any mutations which changed that, and we on the other hand did get those mutations and they helped us out in our particular environment.

Evolution normally happens at a very slow rate. We can't usually see things evolving because most random mutations are not beneficial and do not catch on. But the law of natural selection is really quite simple and makes so much sense I can't see how it could be refuted: things that are different from others in such a way that they tend to survive more are more likely to pass on their genes. Just look at bacteria that evolve because of their resistance to anti-biotics. We kill all the bacteria that don't have immunity to the anti-biotics so only those that can withstand it live on and pass their genes onto the next generations of bacteria, so new antibiotics are required. It happens all the time. Natural selection is an objectifiably observable phenomenon.