I guess I’m so used to having Mel Gibson as Mad Max that I didn’t really register that it was the same character.

And isn’t that kind of the point, really? There was nothing in that movie that reflected Mad Max as a unique character, other than the “badass dude” heroic action-packed stereotype that we’ve seen represented in a hundred other movies. Hell, he talks so little in all of the movies that he might as well be one of those silent protags in an video game.