The Big Bang was the beginning it was the start of space, time, energy and matter. What happened beforehand is taken as unknowable. It may have spawned off another universe. The thing about the Big Bang is it isn't just the matter and energy that was created it was also the laws of physics.

Evolution quite easily explains how humans came into being. It is rather a simple process to create a human from a single cell. It is actually proportionally more complex to create the single cell from the basic building blocks.