Hey! Glad you like these! The Magma Maze expansion has bones similar to what you are talking about. You can find tiles that have a skull, or some ribs, even just a single bone. It has variations with them broken or all together. The Haunted Temple expansion also has some bones, it has some tiles with multiple bones per tile, again including skulls or ribs.
As for blood, this pack doesn't have a patch of blood on the ground currently (that is for sure somethign I can add to an update). That being said I do have blood particles in this base pack.
Likely if I was to add blood it would be to the Haunted Temple expansion as that is kinda the theme of it, creep halloween vibes.
Cheers!