Of course evolution can explain how an amoeba turned into a human -- a series of steps, each driven by natural selection. Not all the steps are known yet, but

Of course evolution can explain how an amoeba turned into a human -- a series of steps, each driven by natural selection. Not all the steps are known yet, but there's no reason to think something else is needed. Complexity accumulates progressively. The origin of life itself is a different matter. This is not well understood. There is a very large complexity gap to the smallest known organism and it's not at all clear how to bridge it. At best we can say we haven't ruled out various kinds of partial theories for how it might have happened.