I don't understand how we'll ever have a "superhuman" AI in any meaningful sense. If by some AI in the far future is ever engineered to (or accidentally) starts

I don't understand how we'll ever have a "superhuman" AI in any meaningful sense. If by some AI in the far future is ever engineered to (or accidentally) starts doing something to destroy humans, we could always repurpose the algorithm to create a counter-AI to solve that problem. The errant AI may cause a lot of damage, but in terms of smarts, it won't be smarter than the smartness humans can harness.