It's perfectly understandable that such things ruin your immersion with the game or cause frustration!
The moving bodies is not you missing any content, it's sadly an engine limitation issue... What happens is, if you exit a room, the bodies end up where the creature/person stood when they were alive, rather than where you killed them. Most games made in the engine get around that by simply not having corpses, or removing them when you exit a room, but for my game that would not have sufficed.
To get the effect working where you can walk under/through some walls, I have to also reset room object positions upon loading a save.
Unfortunately nothing I can do about that, but I understand if it's too much to want to keep playing! Thanks for giving the game a try!