Humans did not evolve from apes, gorillas or chimps. We are all modern species that have followed different evolutionary paths, though humans share a common ancestor with some primates, such as the African ape.
The timeline of human evolution is long and controversial, with significant gaps. Experts do not agree on many of the start and end points of various species. So this chart involves significant estimates.
To say we are more "evolved" than our hairy cousins is just wrong. (See how long you last naked in the Congo Heartland, and then tell me who's got the evolutionary upper hand.)
Thinking that a species evolves in order to survive is to put the cart before the horse. Genetic mutations happen all the time, without fanfare and often without any measurable change in the organism's lifestyle. In general, the mutations most likely to be passed to future generations are those that prove useful to either individual or species survival.
The "usefulness" of a mutation depends largely on shifting environmental factors like those of food, predators, and climate, and also on social pressures. Evolution is a matter of filling ecological and social niches. African apes are still around because their environment has encouraged the reproductive success of individuals with different genetic material than ours.
Evolution is an ongoing process of trial and error, of which all modern primates are still a part.