And I will say, being someone who is a product of every single iteration of MOTU, literally from the beginning (Had the original 8 figures and Castle Grayskull when I was 2 years old)...
The lore is not so crazy deep that it would take that long to catch up on. There IS a lore, don't get me wrong. But we aren't talking Lord of the Rings deep, or even GI Joe ARAH.
And there are several different story variations, but it's simple shit like "Skeletor being Prince Adam's uncle" versus "Skeletor not having a fucking clue who He-Man/Adam is". Just treat it like a choose your own adventure book, and decide which version is your MOTU. My version as a child was just an evil skeleton dude who hated this guy trying to stop him from ruling the universe, but as I got older, I like the familial approach. Kind of felt very Lion King to me, and I dig that.