Stan revolutionized comics with Spider-Man's everyman archetype and soap opera trappings, I'll grant you that. But everything else you mentioned is totally subjective and, at this late stage in the game, entirely moot. Superman may have started out a "strange visitor from another world," but great pains have been made for the last several decades to make him more relatable. Greg Rucka's recent Adventures of Superman run didn't present an implacable alien, it presented a man who bears the weight of the world on his shoulders because he has the powers to make the most difference. Read Joe Kelly's Superman stories and then tell me that he's not every bit as human at this point as any of Marvel's characters. No offense--this may not be the case for you personally--but by and large, it seems that most people who write Superman off as unrelatable simply haven't read that much with him.
I recognize what Supes is presented as now, I'm saying it happened in response to guys like Spidey showing up on the scene.
The Fantastic Four all filled archetypes as much as Superman did initially, too. Reed was the brainy inventor, Johnny was the hotheaded kid, Ben was the stubborn strongman, and Sue was the token girl who never really did anything useful. They've grown far beyond those initial bounds, of course, but so has Superman, by your own admission. Stan Lee got the ball rolling on those kinds of developments and growth, granted, but my argument is--and has been from the start--that in the here and now, neither DC nor Marvel is better than the other at being "down to earth." They've all got fleshed out heroes with a lot of character developments under their belts.
Point taken.
Also, there's something to be said for unrelatability, on the other hand. Gaiman's Sandman is a shining example of godlike characters played entirely as godlike characters and still being completely engaging--even engrossing. And again, Marvel's own Silver Surfer presented a totally unrelatable alien with godlike powers who waxed philosophic on the nature of existence, but he sold well once upon a time. When Marvel recently tried to humanize him by grounding him on Earth and making him interact with humans, it didn't take. That's why this Annihilation Surfer mini has been such a godsend to his fans. He's finally the Surfer we want to see again, not one with the ill-fitting trappings of humanity foisted upon him.