The Jack-O-Man is somewhere between a villager and a mob. So when in the presence of one Iron Golem the Jack-O-Man is attacked by the Iron Golem. If in the presence of two Iron Golems, one will attack the Jack-O-Man and the second will attack the first Iron Golem for attacking the Jack-O-Man.
This goes on till there is but one Iron Golem left attacking the Jack-O-Man.

You have to try it. It is real fun to watch!

That's new. 😆

If we remove IMob from EntityDivineRPGVillager it fixes this. Is there any harm in doing that?

It shouldn't seeing as how it wasn't using any of IMob's variables anyway.