I saw Star Wars this week like everyone else, and yes, it was madly entertaining, and no, it wasn't perfect, and if I want to see a film that's deeply iconoclastic and challenges all my cultural preconceptions I will see something that isn't Star Wars. The part that had my heart in my teeth, though, wasn’t the part I’m not supposed to tell you about. It came a little bit later. It was when Rey, the techie scavenger girl, picks up the lightsaber to fight the bad guy as an equal.

And the music swells. The same old theme and a new kind of hero on a new kind of journey. The same old story made stunning in its sudden familiarity for every girl who ever dreamed of being more than a princess.

Rey picks up her weapon, and everything changes.

In a box-office-pulverising film whose gorgeous effects and point-perfect pacing leave their fingerprints on the back of your eyeballs for days, it says something that the most dazzling feature of all is the female protagonist and her love interest (possibly). Stories about outliers and unexpected heroes have always been around - the difference is that being a woman, a person of colour, a queer person, or some shocking combination of the three does not make you an outlier in quite the same way any more.

We’re allowed stories now that aren’t just "look what she did, despite what she is". Our heroism is no longer quite so unexpected. And that’s as thrilling as it is threatening to those who are used to a single story about white boys winning the day.

The way we tell stories is changing. The change is creeping slow and political as hell. Just look at the diverse stories we’ve had this year, none of them perfect, all of them groundbreaking in the simplest and most shocking of ways. It’s Jessica Jones and Kimmy Schmidt. It's Steven Universe. It’s Orange Is The New Black and How To Get Away With Murder. It’s Black Hermione and female Ghostbusters. It’s Transparent and Welcome To Night Vale. It’s Gamergate and the Hugo Awards. It’s Mad Max. It’s Star Wars. Diversity shouldn't be exciting by now, but it is.

And of course, the backlash is on.

People who are quite happy to suspend disbelief in superpowers, summoning spells, dragons, aliens, planet-destroying starbases and Mark Hamill's acting abilities somehow find the idea of, for example, a black Hermione a bit too much and react with death threats and hate-mobs. This week, when the internet learned that a black woman had been cast in a new play billed as the ‘next instalment’ in the Harry Potter series, author J K Rowling reacted perfectly, reminding fans: "Canon: brown eyes, frizzy hair and very clever. White skin was never specified. Rowling loves black Hermione".

Was Rowling imagining a black girl when she sat down to write that book in the mid-1990s? Probably not. But she knows, like the best storytellers, that books are hands held out to lonely children of every age, and not all those lonely children are white boys, and those stories change lives in ways even their authors cannot guess. So it matters. It matters that the "brightest witch of her generation", the bookish heroine of a generation’s definitive fairytale, doesn’t have to be white every time.

Let's not get carried away here. These stories and retellings are still exceptions. Women are still paid less, respected less and promoted less at almost every level of every creative industry. For every Jessica Jones there's a Daredevil, whose female characters exist solely to get rescued, provide the protagonists with some pneumatic exposition, or both. For every Orphan Black there's Mr Robot and Narcos and you know, sometimes I wonder if perhaps I watch too much television. The point is that what we have right now isn't equality yet. It's nothing like equality. But it's still enough to enrage the old guard because when you've been used to privilege, equality feels like prejudice.

The rage that white men have been expressing, loudly, violently, over the very idea that they might find themselves identifying with characters who are not white men, the very idea that heroism might not be particular to one race or one gender, the basic idea that the human story is vast and various and we all get to contribute a page - that rage is petty. It is aware of its own pettiness. Like a screaming toddler denied a sweet, it becomes more righteous the more it reminds itself that after all, it’s only a story.

Only a story. Only the things we tell to keep out the darkness. Only the myths and fables that save us from despair, to establish power and destroy it, to teach each other how to be good, to describe the limits of desire, to keep us breathing and fighting and yearning and striving when it'd be so much easier to give in. Only the constitutive ingredients of every human society since the Stone age.

Only a story. Only the most important thing in the whole world.

The people who are upset that the faces of fiction are changing are right to worry. It's a fundamental challenge to a worldview that's been too comfortable for too long. The part of our cultural imagination that places white Western men at the centre of every story is the same part that legitimises racism and sexism. The part of our collective mythos that encourages every girl and brown boy to identify and empathise with white male heroes is the same part that reacts with rage when white boys are asked to imagine themselves in anyone else’s shoes.

The problem - as River Song puts it - is that 'men will believe any story they're hero of,' and until recently that's all they've been asked to do. The Original Star Wars was famously based on Joseph Campbell's "Hero's Journey", the "monomyth" that was supposed to run through every important legend from the beginning of time. But it turned out that women had no place in that monomyth, which has formed the basis of lazy storytelling for two or three generations: Campbell reportedly told his students that "women don't need to make the journey. In the whole mythological journey, the woman is there. All she has to do is realise that she's the place that people are trying to get to".

Which is narratologist for "get back to the kitchen" and arrant bullshit besides. It's not enough to be a destination, a prop in someone else's story. Now women and other cultural outsiders are kicking back and demanding a multiplicity of myths. Stories in which there are new heroes making new journeys. This isn't just good news for steely-eyed social justice warriors like me. It also means that the easily bored among us might not have to sit through the same dull story structure as imagined by some dude in the 1970s until we die.

What does it mean to be a white cis boy reading these books and watching these new shows? The same thing it has meant for everyone else to watch every other show that’s ever been made. It means identifying with people who don’t look like you, talk like you or fuck like you. It’s a challenge, and it’s as radical and useful for white cis boys as it is for the rest of us - because stories are mirrors, but they are also windows. They let you see yourself transfigured, but they also let you live lives you haven’t had the chance to imagine, as many other lives as there are stories yet to be told, without once leaving your chair.

This isn’t just about "role models". Readers who are female, queer or of colour have been allowed role models before. What we haven’t been allowed is to see our experience reflected, to see our lives mirrored and magnified and made magical by culture. We haven’t been allowed to see ourselves as anything other than the exception. If we made it into the story, we were standing alone, and we were constantly reminded how miraculous it was that we had saved the day even though we were just a woman. Or just a black kid. Or just - or just,whatever it was that made us less than those boys who were just born to be heroes.

The people who get angry that Hermione is black, that Rey is a woman, that Furiosa is more of a hero than Mad Max, I understand their anger. Anyone who has ever felt shut out of a story by virtue of their sex or skin colour has felt that anger. Imagine that anger multiplied a hundredfold, imagine feeling it every time you read or watched or heard or played through a story. Imagine how over time that rage would harden into bewilderment, and finally mute acceptance that people like you were never going to get to be the hero, not really.

Then imagine that suddenly starting to change. Imagine letting out a breath you’d held between your teeth so long you’d forgotten the taste of air.

Capitalism is just a story. Religion is just a story. Patriarchy and white supremacy are just stories. They are the great organising myths that define our societies and determine our futures, and I believe - I hope - that a great rewriting is slowly, surely underway. We can only become what we can imagine, and right now our imagination is being stretched in new ways. We're learning, as a culture, that heroes aren't always white guys, that life and love and villainy and victory might look a little different depending on who's telling it. That's a good thing. It's not easy - but nobody ever said that changing the world was going to be easy.

I learned that from Harry Potter.