There are several prominent theories, but the consensus in the scientific community is that life did not spontaneously begin. It was a long, drawn out process of trial and errors.
Some theorized that single cellular life began deep in the oceans near vents in the ocean floors. They eventually became multicellular when resources were used up and they necessitated a community to survive.
Others theorized that life began on land, in a hot spring of sorts - which has had recent evidence uncovered in support of this theory. From there life went many directions.
If you're looking for human life specifically, then Africa would be a good answer. That's where our closest relatives live and evidence shows that early tribes originated in Africa, then traveled different directions to eventually for the races and communities we have today.
Life from non-living matter could have been brought to earth on a meteor or asteroid in the form of amino acids, which are the basic building blocks to life. They could have also formed from the elements by pure chance. The only answer I have in that respect is that I highly doubt there will ever be a definitive answer to that question.
Science is awesome.
