Imagine if the Thor movie had been something like actual Norse myths, possibly along the lines of Tsui Hark directing Nicolas Refn's Valhalla Rising from a From Hell-era Alan Moore script. Stone and ice and blood, so grimly dark that it couldn't be called nihilist only because that's the easy way out. There's a reason none of those names are associated with Hollywood or even America - because that's exactly the kind of film nobody there wants to make (though they like to pretend The Dark Knight is such).
But then Thor comes at the mythology at two removes. First Stan and Jack pilfered the originals (which have come down to us in less-than-original form but there's nothing that can be done about that) for pieces. So Loki was Odin's blood-brother (at least in some versions) now shifted to Thor's adoptive brother. Sif gets a sword and her hair changed from blonde to brunette (more interesting considering that at least two entire myths revolve around her blonde hair). And Thor himself loses a beard and has his hair changed from red to blond making him look...well Aryan. Gone as far as I can tell (the Thor comics have never interested me much) are the stories about how Odin lost his eye and acquired wisdom, the hall of the dead, the constant combat, and of course how Loki changed himself into a female horse, got mounted by a stallion then gave birth to Odin's eight-legged horse Sleipnir.
The movie moves even further to the point that it hints all the gods are just aliens and the magic just technology. Odin becomes even more the kindly patriarch than in the comic. You knew that no movie would ever use Thor's goat-drawn carriage which honestly may not be in many of the comics but is at least used in Simonson's run.
The reason I'm bringing up all this is because of the common tendency to compare superheroes to a modern mythology. It's presented almost that bluntly like we're supposed to stroke our chins and go "mmm modern mythology how deep and wise". In Grant Morrison's new Supergods he even claims to explore this but beyond comparing the looks of some characters to gods (such as Hawkman to Horus) he doesn't go any further, not even whether these characters were in fact based on any gods whatsoever.
But what would this mean? Does saying superheroes are mythic or their stories a mythology mean anything?
One problem is the very concept of mythology. They way it's presented to most of us in a standard education is that myths are (a) stories that explain something about the world and (b) the religion or religion equivalent of early ("primitive") socities. But even if you didn't know about the vast centuries-old academic debate concerning myths it would be obvious that "mythology" is a very elastic term. Some myths are explanatory and some are wisdom tales but large numbers are just as easily entertainment or historical or warnings or simply cryptic. The story of Pyramus and Thisbe does end up explaining the color of mulberries but it's quite a complicated (though short) method for such a purpose. Did the Romans only care about mulberries? Did the thousands of stories explaining every fruit and plant not come down to us? Was the story intended for more tragic purposes? (Which might explain what attracted Shakespeare to remake it and later parody it.) Was the love story the purpose and the mulberries just an afterthought? Or what is the point of Leda and the Swan? Or for that matter Loki giving birth to Sleipnir? What on earth could that possibly explain?
It doesn't help that most of us encounter myths in cohesive stories with the contradictions generally removed - instead of the numerous conflicting and often fragmentary originals it's Edith Hamilton. Now I wouldn't knock Hamilton or Bulfinch or the D'Aulaires but the point is that the original myths are messy but we learn them cleaned up and then have simplistic reasons for their existence taught to us. The original myths do sometimes explain things and were in fact sometimes religious (though not always in quite the way we might think about that). But they served numerous other functions from pure amusement to preserving historical memories (the latter even has its own name "Euhemerism").
So I think you can see what this might have to do with superheroes. Most people claiming superheroes=modern myth are trying to latch onto something grandiose but really it's true more because superheroes are stories about beings with unusual abilities and like myths are often contradictory and fill many functions. I don't think that Superman appeals to us because he's a sun god (as Morrison claims) otherwise Supreme or Hyperion would be just as popular. (Though it's worth noting Warren Ellis named his Superman clone Apollo. (And since this is comics by "clone" I don't mean an actual clone of Superman (such as the current Superboy) but a character modelled on Superman.))
So if Hercules/Herakles can go through all his adventures (choking snakes, twelve labors, searching for the Golden Fleece, murdering his family) then in many ways that's similar to a superhero's origin and varied exploits (minus the family-murder unless it's Irredeemable I guess). Sure they're not all that similar but my point is that myths are at their core stories and more specifically stories beyond the everyday. In addition to all the other functions myths were meant, at least at times, to entertain, a word that's come to mean something of little real consequence but in some sense is what most art is intended to do (the whole amuse-and-instruct thing with or without the instruct). So I see superheroes=myth not as tapping into any archetypes (which seem dubious to me at best) but more in the area of variant stories, sometimes conflicting and sometimes of opaque purposes.
Yep, a long post for such a tiny point but hey that's the Internet.