Simply mimicking the human brain in an attempt to produce intelligence is akin to scavenging code off the web to write a program. Will you understand well how the program works? No. Will it work? If you can hack it, very possibly.

It seems that we're only just beginning to learn how to hack nature. Personally.. I'd say it's a much more likely way to AI than deliberate design. But that may be just because I don't think humans are collectively that bright.