Here are some of the things that Peter Parker, aka Spider-Man, gets up to in the course of his new movie, The Amazing Spider-Man: he shuffles along the hallway of his school, mumbles, gets bullied, rides his skateboard, skips class, fails to finish his sentences, broods like James Dean over his parents, catches a cab, catches a subway, smashes an alarm clock, and has Branzino for dinner with his high-school crush Gwen Stacy.

"This Spidey reboot refreshes an old story through the on-trend notion of making a Marvel superhero less super-heroic" noted Lisa Schwarzbaum in Entertainment Weekly.

Not that he doesn't get up to his usual tricks — swinging through the canyons of New York, saving kids from burning cars, and fighting off giant green lizards — but it's a full hour before he is seen in full costume.

"Nobody knows anything," as William Goldman famously said about the movie business, but in a summer movie season crowded with multi-million dollar movie franchises, all bearing down on one another like Porsches in a demolition derby, here is one law of summer movies which stands firm: the less time the superhero spends in costume the better the movie.

Cast your mind back to The Avengers, that gentle chamberpiece of May, featuring a running flush of superheroes.

The ones everyone came out talking about, however, were the only two with lives outside the unitard: Robert Downy Jr's cocky playboy-industrialist Tony Stark and Mark Ruffalo's gently beleaguered Bruce Banner, who spends the entire movie refusing to turn into the Hulk.

"Ruffalo's unchanged mug gets 20:29 minutes of screen time," noted New York's Vulture, approvingly. Ruffalo's reviews were so good there was immediately talk of him getting his own movie.

Then there is the new Batman movie, The Dark Knight Rises, the final part of Christopher Nolan's trilogy, which follows Spiderman into theatres on June 20th.

Universally praised for restored lustre to a franchise left for dead in the mid-nineties when Joel Schumacher reintroduced Robin, dressed Arnold Schwarznegger in silver lame, and gave the bat-suit bat nipples, Nolan uses Batman much more sparingly.

A batfan at SuperheroHype recently number-crunched the amount of screentime enjoyed by Batman and came up with the following figures:—

Batman – 21%

Batman Returns – 17-18%

Batman Forever – 19%

Batman and Robin – 15%

Batman Begins – 16%

The Dark Knight – 16%

Batman and Robin is the outlier here, but otherwise the message is clear: less is more. Batman's shortest scene comes in Batman Begins – a mere 15 seconds "perched on a skyscraper" – by far the most beautiful and memorable shot of the entire series.

By contrast, Batman is all over the Schumacher and Tim Burton films like a rash, whether "Saving first-born sons" (0.08) "Staring the Joker in a helicopter" (0.89) or "Infiltrating Penguin's layer" (3.33). He reaches a pitch of ubiquity in the overhyped 1989 film, parading himself for a full 29 minutes of screentime, thanks to the writers' decision to fast-forward through the Bruce Wayne backstory. "You had to wade through 20 years just to get to the first shot of the guy in the costume that we've all come to see," they said, getting things almost exactly wrong.

It's an easy enough mistake to make. Pollsters will tell you there is a world of difference between what people say they want and what they actually want.

We say we want to see Superman, but what we actually want is to see is that transfigurative moment when Clark Kent runs across the street looking for a phone booth, peeling his shirt back to reveal the 'S' on his chest and "smack down the bullies of the world," as one of his creators, Jerry Siegel, put it.

A superhero without an alter ego is just a megalomaniac in a cape. "Only a weak man knows the true value of strength," said Stanley Tucci, in last year's Captain America, one of the few recent films to understand the form's genesis not as power trip but wish fulfilment.

Comic books are by, for and about those who are weak, not strong. In his excellent history of the genre, Men Of Tomorrow: Geeks, Gangster and the Birth of the Comic-Book, Gerard Jones makes clear the parallel between the double lives of the superheroes and their creators, those scrawny, near-sighted, cripplingly timid immigrant Jews from the Lower East Side of Manhattan, dreaming of Douglas Fairbanks, He Men, and Charles Atlas during the depression:

"Clark Kent playing at cartoony mundanity, then bursting free into hallucinatory grandeur before cloaking himself at the end and winking knowingly to the reader. It was an allegory that echoed for immigrants and Jews: the strange visitor who hides his alien identity so as to be accepted by a homogenous culture."

Sympathy for the underdog had a resonance beyond just the Lower East Side of the 1930s, however. Table-turning, nick-of-time empowerment is built into America's founding myth: that of the scrappy, oppressed nation that one day decided it had had enough sand kicked in its face and stood up to its imperialist tormentor. In one sense, the Declaration of Independence is nothing but Clark Kent removing his glasses, writ large.

That's what makes the superhero genre — for all its excesses, and annoying cultural ubiquity — such a fascinating, florid window into the national psyche. If you want to know how America felt about itself after defeating the Nazis, look no further than the rippling musculature and high-impact punches of Jack Kirby's work for Marvel, during the comic's so-called "silver era":

"Kirby celebrated the body, the male body, male sweat and muscles, not with the fetishism of body building but with savage joy … The underfed ghetto kid transformed into a roof rattling power by seizing American opportunities, the weary old country survivor reborn as the new fighting Jew through the crucible of America freedom and violence. And through that immigrant passion Simon and Kirby captured an entire national awakening America the provincial stirring itself to become a world power."

That is why today belongs to Marvel, in every sense. There is no better image of America's isolation as the sole remaining superpower than the endless sequence of superheroes trolling across our screens, no longer bothering to impersonate human beings but blasting away at each other like Greek Gods, for want of anything better to do.

As A O Scott commented in The New York Times recently: "Far from being an underdog genre defended by a scrappy band of cultural renegades, the superhero spectacle represents a staggering concentration of commercial, corporate power."

That's why it's so heartening to see Andrew Garfield fumbling his vowels in front of Emma Stone. Not that it isn't always a pleasure to see Emma Stone, who joins Jon Stewart, Louis CK and the films of Pixar as one of the chief reasons to feel cheerful about America right now. Sometimes it pays not to be super. But then you knew that from The Incredibles.

"Everyone's special, Dash" says Elastigirl, aka mom.

• Note: This piece has been corrected to show that Jerry Siegel, not Joel Siegel, was a creator of Superman.