Sometimes you don't see victory coming. It's been a long slog since the disaster of Saratoga and the humiliation of Yorktown but at last the empire has struck back. It's been tough – they've spent decades making us feel puny and irrelevant. We've relied on them for money and troops. They almost made us forget there was a time when we could launch disastrous invasions of Afghanistan without their help. But finally it seems that the American colonies' 235 year flirtation with independence is coming to an end.

Praise be: all three of the great American superheroes-of-state have fallen into British hands. British actor Henry Cavill has just been cast as Superman in Superman: Man of Steel (presumably the sequel to the more controversial Stalin: A Super Man). And that completes the set: Christian Bale, the British child from Empire of the Sun whose accent is now located about where the Lusitania sank, is the current Batman, and Surrey's own Andrew Garfield is "rebooting" the Spider-Man franchise, bringing New York's arachnoid crime fighter to a whole generation who were too young to catch the final instalment of the previous Spidey trilogy, way back in 2007. If only someone had recorded it.

But let's leave aside the fact that Hollywood is now reimagining Superman and Batman twice each for every time I descale my shower-head, and Spider-Man more often than I change my mobile phone tariff, and rejoice in having turned the tide of cultural imperialism. Stateside acclaim for The Madness of King George, Mrs Brown, The Queen and The King's Speech is all very nice but it has the patronising quality of a parent commending a precocious child on having sent up a teacher in a school play. If we were ever going to curb American self-confidence, we needed to strike at their equivalent of royalty: made-up magical people from comics.

Yet, even in the moment of conquest, I had my doubts (as Tiger Woods used to say). So I looked below the British newspapers' jingoistic headlines and read the actual articles – or, as I call them, "the small print". It turns out that Garfield was born in Los Angeles and has dual citizenship, Cavill is from Jersey, not the new one but it still isn't part of the UK, and Bale largely grew up in Hollywood. I say "grew up", I suppose I mean "became older". It looks, from YouTube, like he's a bit of a Peter Pan when it comes to professional conduct.

Still, they're a bit British – they're British-influenced. Cavill was in The Tudors and went to Stowe School, Garfield's been on Channel 4, and not just in a Frasier repeat, and Bale was born in Wales. He's slightly Welsh and you can't get more English than that, unless he was also a quarter Scottish with an Irish great grandparent. So it's still something, right?

Not really, not any more. This is how Charles Gant, film editor of Heat, explains the new global reality: "Superman, Batman and Spider-Man might be American icons, but the primary revenue streams for these films are outside America." The important demographic, our future Asian paymasters, neither care about nor discern the difference between Britons and Americans. If Cavill's American accent's a bit shaky, they won't give a damn. We're all just impecunious round-eyes, shaking a tail feather in front of a green screen – trying to make a quick yuan to set against our astronomical debt.

The British are the new Canadians. We're not taking over American culture, we're being absorbed by it, and at the very moment when its influence is starting to wane. We're infiltrating a dying empire, like the Scots did when they took over Westminster politics.

This leaves me feeling ashamed at having enthused about British involvement in superhero movies in the first place – it's not as if I like them. It feels like rooting for Andy Murray. You can suppress misgivings that he's moody and annoying for as long as he's still in a tournament but, when he loses, the fact that you've expended emotion supporting someone you don't know, whose fortunes don't affect you, and the cut of whose jib you don't particularly like, makes the disappointment turn even sourer.

Today's Hollywood pumps out superhero stories like it once did Westerns. Not just the three superheroes of record but spoofs such as Mystery Men and The Incredibles, superhero gang shows like The Fantastic Four and X-Men, and the TV series Heroes and No Ordinary Family (which, from the trailers, looks like a non-spoof version of The Incredibles). It's so relentlessly two-dimensional. And I concede that there are two: the characters don't just have superpowers, they also find that strange. So, you know, bravo.

Is this the final infantilisation of entertainment? Are we the first generation of adults who, when we reached maturity, did the cinematic equivalent of giving ourselves crisps and chocolate for every meal because we never had the concentration to develop other tastes? Most of these films, however exciting their action sequences, are deeply silly.

Yet some critics make artistic claims. I quite enjoyed Batman Begins but those who wax lyrical about what a disturbing character Bruce Wayne is, and claim that whichever comic it's all based on merits comparison with a proper book full of words, have lost sight of the bigger picture: it's all about a man so rich and mental he hangs around the streets at night, dressed as a bat, trying to drop on burglars. This is a daft story which, if it were true, would only be fit for a Channel 5 documentary about a disreputable Kevlar salesman exploiting billionaires with personality disorders.

I think we Brits might have been wiser to stick to playing villains. It may not get the big money but it's steady work and the villains in Hollywood superhero films are fairly similar to the heroes of British popular culture. Sherlock Holmes, Hercule Poirot, Raffles and Doctor Who all have far too many ambiguities and nuances to be Marvel comic goodies.

Some readers will refute this point by citing character ambiguities and nuances such as "obsessively pretending to be a bat every night" and "finding it unsettling to develop the powers of a spider", but we'll have to agree to differ. Just like Agree-to-Differ-Man who was bitten by a radioactive Liberal Democrat and travels the universe resolving arguments while sitting on his jet-powered fence. That's a role that only someone British could play.