Your arguments seem to also apply to humans, and clearly humans have figured out how to be intelligent in this universe.
Or maybe you're saying that brains are taking advantage of something at the quantum level? Computers are unable to efficiently simulate quantum effects, so AGI is too difficult to be feasible?
I admit that's possible, but it's a strong claim and I don't see why it's more likely than the idea that brains are very well structured neural networks which we're slowly making better and better approximations of.