You are severely under-estimating carbon based life forms. These were designed for over millions of years in differing circumstances. Humans are not the only carbon based life form. A bacteria might not be that smart but it'll pro-create it's way to create the human, or its equivalent depending on the environment.

In my opinion, carbon based life forms are the most optimized solution to the problem. It'll be very hard (or close to impossible) for humans to come up with an alternative. Only if we master infinite energy and infinite computation, we might stand a chance to replace that.