Piglins and zombified piglins wear mobs heads but most monsters used to wear them but not anymore. here are the following mobs that dont wear mob heads anymore
Zombie
Husk
Zombie Villager
Drowned
Skeleton
Wither Skeleton
Stray
and Piglin Brute
please fix this and update minecraft so that those monsters can wear mob heads again
Cannot reproduce: dropped a skeleton head on a zombie villager in creative mode it picked it up and put it on.
Note that not all mobs can pick up items. The chance that they can pick up items depends on the game difficulty setting. The mob griefing option must also be enabled.