[bermanoid]

Evolution did just fine, and it's far more scattershot than our current efforts at AI.

You're also crucially missing the possibility that someone comes up with an intelligent algorithm that doesn't mirror the human brain in much detail, but still manages to outperform it. Think of flight: inventing flapping machines didn't turn out to be very useful, but we figured out a workaround that was far more efficient. The most interesting (terrifying?) AI research is along these lines.