oh, so the campfire, home, and necromancer den are the only constructions that can't be freely placed. that's not a bug.
I did notice getting stuck in the Necromancer den when placed, I fixed that for next update.
I haven't considered a bestiary, partly because I never thought there was enough creatures to justify it. But It could make things to easy for the player. part of the fun I think is the unknown.
There are a lot of creatures hiding around in the game, that aren't very common, dragons and unicorns and other things, I think it would be more fun to discover them while exploring.