Mad Max for sure.
I dont think this movie needs a complex origin story just make it simple like the Mad Max and Terminator films.
He-Man was a
barbarian from an
Eternian tribe. The planet's inhabitants were dealing with the aftermath of the Great Wars, which devastated the civilizations which once ruled supreme. The wars left behind advanced machinery and weaponry, known only to select people. An early incarnation of the
Sorceress of Castle Grayskull gave He-Man some of these weapons, and he set out to defend the secrets of
Castle Grayskull from the evil
Skeletor.
Make it a simple story of He-Man in an post apocalyptic world getting about having to slay beasts on his quest to destory Skeletor.
