I am also getting a significant amount of NPCs with unlimited health.
EDIT: Tried using both Super Cowboy and Unlimited Health, it gives rando npcs unlimited health either way.
[Edited by Szerath1, 9/20/2020 11:42:27 PM]
I've tried a few things and I am pretty sure it is the 'No Fall Damage' option.
I was encountering immortal NPCs and animals, but since switching this option off and running with both 'Super Cowboy' and 'Unlimited Health', I have been able to kill without issue so far