I wanted to tie the game into the theme in a bunch of ways, but the main one is the concept that society is falling down to the face of the earth, after the ravens came down to earth and spread the plague. There are other smaller tie-ins as well.
Not exactly falling, but yes, as birds I’d say they came from the sky. In the game the ravens have a sort of supernatural background, so I’m not going to say they came from Earth... if you look into it there’s sort of a collision of worlds in a way ;)