I am not going into the religious perspective. I am a believer in God but will answer as per your question.
Scientifically speaking, evolution happened gradually. The humans were not the first species to have arrived on this planet. it is said that aquatic animals were the first and then evolved into land animals.
As for monkey to human - it is highly probable. we can see the similarities between monkeys and humans. After all, there is scientific proof to show that early humans were not very intelligent when compared to the present humans.
Each generation of humans is evolving and more intelligent than the previous ones. ( differently abled and other such malformed births are there and am not referring to such instances)