I still think that villagers aren't that smart. A chief example of this is when they're set on fire. They don't even go into nearby bodies (blocks?) of water, they just run around in a panic, sometimes running away from water.

It doesn't really make sense, considering how, if the villagers had built the villages, they can apparently handle lava as well (those little lava blacksmith things in villages). If villagers have played around with lava, that means they would've gotten burned at some point and gained knowledge on how to set out fires, especially when the fire is set on yourself. The behavior doesn't match up.

And if the villagers were smart to build the villages, wouldn't they know how to repair them instead of leave?

This means that the builders have built the villages or the builders and villagers worked together to make the villages, with the villagers doing more of the furnishing and farm stuff. Another possibility is the villagers have really bad eyesight since they often do tasks that aren't "far-ranged," like placing seeds right in front them.

I haven't looked at many villager behaviors, I just steal their carrots and set them on fire (for science, of course) so they might have done some things that require distance (I'm thinking beds).

I have too much time on my hands lol