It's annoying how things like this always attract lorefags, because "mUh WoRlDbUiLdInG" usually adds nothing to the original concept. A typical creepypasta mistake is assuming that more explanation = good writing.
Personally I think the Backrooms is creepier with no monsters in it: just an endless, lonely labyrinth of disgusting carpet and buzzing lights until you eventually go mad enough to bash your head against the wall. But I can understand why people are adding monsters for the sake of entertainment.