Perhaps its already been modded or suggested, but I’m surprised there aren’t any creatures in the game that play possum or of the ambush type. Entities that lie in wait until ambushing prey that gets too close whether its you, npc, animals, or opposing creature-faction. Could make it so perception & trapping skill increases odds of detecting ambushes.
[sleeper Zeds] - appear in game as dead human bodies, until one gets too close.
[trapdoor spiders] - giant trapdoor spiders that set up in forests,etc.
[Brown Snakes/Possums] - will play dead if anything spooks it or gets too close.
These are the few I can think of, but will spice things up a bit. Sometimes it feels a little too safe to loot dead bodies or walking through the woods.