Hmmmm

Okay so, I went back and read all 12 again.

Why do they kill the Zombie/maggots if they don't bite or anything? What do they actually do?

Dumb me just read the prologue. Damn, Guwon literally rose from rubbles. What is he? A failed experiment? Kept locked in and as the building came crashing down he got released. That would make a lot of sense considering all his actions.
- doesn't know most things, as a person locked up their whole life wouldn't.
- doesn't remember, as someone going through multiple experiments wouldn't want to remember.
- everyone is scared of an object of experiment they don't want getting loose.

And much more....

Guwon's actions feel very genuine. But if it's all an act he's one hell of an actor crying in the blink of an eye like that asking if Heo is scared of him too or not.

Does Guwon ever eat? Does it mean anything? He fed teach but never seen him eat.

Someone pulled a theory a few comments back that his head is someone else's based on the stitch marks, go read that. It is a really good theory, just wanted to mention, his ankles has similar marks too.

The Sisyphus boulder is the moon shaped one Guwon talked about before butchering that maggot on the hill.