It's simple. Do you know how, once we applied human brain power over the problem of flying we managed, in a matter of decades, to become better at flying than nature ever did in hundreds of millions of years of natural selection? Well, what do you think will happen now that we're focused on making AI better than brains? As in, better than any brains, including ours?
AI is catching up to human abilities. There's still a way to go, but breakthroughs are happening all the time. And as with flying, it won't take thousands of centuries of research and development until we make that happen. It'll take decades.
And once that happens, bye, bye, relevance of human brains for problem solving. AI will have solved it before you managed to articulate the problem.