How human came into existence?

Perhaps no one really knows how human came into existence. People who are religious would say god put us here.

Then came the theory of evolution, changes on molecular level begins and after a period of time human formed to what we see we are today. Scientists and archaeologist have from time and time again back this theory with findings of ape skull that reassemble skull structure of that to human.

Another obscure theory of life evolution was that all life originates from ocean. Later, mutations enable ocean species to have breathing organ and adaptations to live on land begin.

The far more fictitious theory includes alien creation of life by putting life species here on Earth and let it evolves. Observation is done from a far. The aliens would come back to Earth for studying the humans and life forms without revealing themselves or refuse to make contact with human on Earth.