"Humans. As opposed to what?"

It might be weird that he does actually seriously consider her challenge instead of getting annoyed. "If I choked on vomit or someone stabbed me, I'm sure I'd wake up at least enough to realize I was dying. Plus, I went to sleep in my dorm on the UA campus. With all the extra security, there's no way anyone could have snuck in at this point, much less gotten past dozens of pro heroes and provisionally licensed students to kill me specifically." Or Ochako, for that matter.

There it is again, the implication that she might not be human - even as a counterpart to Hell, 'the human world' suggests a level of otherness that wouldn't occur to most people.

"There are plenty of Quirks out there that could accomplish all this and more. Illusions, spatial manipulation, mass displacement, electrification - All for One and his lackeys could easily possess a combination of Quirks that could run a place like this on its own indefinitely, not to mention other villain groups that might exist."

Or non-villain groups, but that seems a lot less likely.

"Hmm. I think I remember a storm, too. But what do you mean by 'devil'?"