> I think the reason for this is that our brains just generally don't operate on a rational basis because it's not practical for humans.

Not meaning to pick on you, but this line of reasoning is ultimately self-refuting.

If we're not capable of operating on a rational basis, then the belief that "we're not capable of operating on a rational basis" is itself irrational and therefore shouldn't be believed.

Since this is self-refuting it must not be true and therefore we must be capable of operating rationally.