What you seem to be missing is that the post-apocalyptic setting plays into everything. The look, the characters, how they function. Get rid of the space in Star Wars, and suddenly it is very similar to a lot of things. Heck considering Lucas ripped many of the ideas and specific scenes from other places. But Star Wars is a landmark in filmmaking, a true turning point, and something cinema has never seen before. In 1977, there was nothing fresher then Star Wars. Now think about Harry Potter or Pirates of the Caribbean, or GotG. All are referenced to Star Wars.
Max is the cliched "Man With No Name". But he is different, a product of a very different environment. The characters who populate a very different world, and because of that they are different. The Humungus is a flippin' pro wrestler. Look at his speeches, his attire.
You bring up Seven Samurai. A film you seemingly haven't seen, and then miss the point. It is all about the setting, the characters, the Samurai culture. The Magnificent Seven is a remake, and still doesn't have the same tone or character of Seven Samurai. Yojimbo and A Fistful of Dollars are far closer, and that would be because Yojimbo is very much a Japanese Western.
I know this is wiki, but I can't find it anywhere else. Here is Kurosawa on the Magnificent Seven:
Also, who calls Seven Samurai, the original and far superior film, Kurosawa's Magnificent Seven. What the hell?