The people from the studio didn't really seem human to me. The cruelty aside, how did they literally appear in Jong Woo's dream? I mean sure he was paranoid, but just living with weird people shouldn't make you have nightmares every night. In the beginning, it wasn't even that bad yknow. What was the problem? Moon Jo himself was really fast when he was stalking people. How did he disappear so fast? 

Might just be humans honestly. Moon Jo might be some sort of creature though since it's really difficult to explain how the hell he does the stuff that he does.