With the release of Man of Steel looming, we examine why the Superman story retains such power after more than 70 years

A movie trailer for this year's eagerly awaited update of the Superman story contains a moment which appears to subvert one of the most famous characters in the American cultural landscape. At first the trailer recounts the familiar story of a child from a distant planet, raised by farmers in Kansas who seek to keep his powers secret and call him by the human name of Clark Kent.

But after saving a bus full of schoolmates from drowning, a traumatised teenage Clark confronts his stepfather, who is worried he has revealed his true nature. "What was I supposed to do? Just let them die?" Clark asks. His father replies: "Maybe."

It is a shocking piece of moral ambiguity in the Superman universe, where what is right and wrong have traditionally been clear. Along with a mournful soundtrack and arty shots, it is the strongest hint yet that the Superman of 2013, played by British actor Henry Cavill, is going to be rather different.

Since his first appearance in Action Comics in 1938, Superman has adapted to changing times. After the second world war broke out, he changed his slogan from fighting for "truth and justice" to fighting for "truth, justice and the American way". That continued during the 1950s, when he became a symbol of muscular American patriotism which could do no wrong.

But as the nation grappled with the turmoil of the 1970s and embraced a more diverse culture, Christopher Reeve gave Superman more human qualities. In Richard Donner's 1978 film version of the comic book saga, self-sacrifice suddenly became part of Superman's appeal.

That continued through to the 2006 movie starring Brandon Routh when, with an evangelical Christian in the White House and much talk of the war on terror being a conflict with Islam, Superman was depicted almost as a Christ-like figure. Even as recently as this year, the latest DC Comics story had Superman pack in his newspaper job to start a blog.

"Superman changes with remarkable rapidity and yet manages to paradoxically project an idea of unchanging virtue," said Professor Benjamin Saunders of the University of Oregon, author of an academic study of superheroes called Do The Gods Wear Capes?

So what will the Superman of 2013 look like? Even with the familiar tropes of a Kansas childhood and the Clark Kent alter ego, he is likely to reflect our modern world, which is uncertain and fearful of collapse, whether economic, political or environmental.

By seeking to reflect these troubled times Zack Snyder, who is directing the new film, called Man of Steel and scheduled for release in June, will be tinkering with one of the most powerful fictional figures of the 20th century. Fans often like to debate which superhero might beat another in a fight, but in the realm of image-marketing there is no doubt – Superman wins every time. "He is the first global superhero," said Larry Tye, author of Superman: The High-Flying History of America's Most Enduring Hero.

Indeed, Superman's influence is so great that he is spearheading the growing academic study of comic heroes and their role in society. Such figures are seen as fulfilling the same societal function as the myths of ancient Greece or Rome. They are outlandish creatures doing battle for high ideals and teaching us moral lessons. "We need myths to teach us virtues. Eventually those virtues need to be embodied by a person. Mythology has always played that function," said Professor Harry Brod, a philosopher at the University of Northern Iowa.

Some have taken the point of the moral teachings of Superman stories further, seeing a powerful philosophical concept behind them. In his book Saunders devotes a chapter to Superman, in which he suggests that the character's immense popularity is a result of his embodiment of goodness. "In terms of 20th-century popular culture, he captures the notion of a Platonic ideal of the good. When Superman is done well, I am not embarrassed to call him a beautiful idea," Saunders said.

Other experts in how human cultures work go even further in their efforts to explain the extraordinary longevity of the Superman figure.

The 2006 film that made Superman into a Jesus Christ-like figure was perhaps closer to the core of Superman than any other depiction. Just take some of Superman's main attributes. He descends to Earth from a world far away up in the sky. His true father passes him advice as he walks among mere humans.

Except if you think he is Moses. With a slight change of emphasis, one can look at Superman's origin story and see an orphan from a people whose home world has been destroyed. He is raised by an adoptive family as one of their own, while hiding his true identity. It is not much of a leap to see the story of Jewish exile in Egypt there.

In fact, the Jewish origins of Superman have sparked immense interest. The original comic book character's creators, Joe Shuster and Jerry Siegel, were both Jewish. Brod has written a book, Superman is Jewish? that traces Jewish themes in the story. Some are religious, like the Moses parallels, but others are based in more contemporary views of modern Jewishness. For example, Superman is an outsider in the world in which he finds himself. He is literally an alien. His alter ego Clark Kent is a geek, hiding behind glasses and posing as an intellectual rather than a physical hero.

In putting Superman in such clothes, Brod sees a Jewish male fantasy playing out – but one that resonates with mere mortals everywhere. "Clark Kent is timid. He is a Jewish nerd. He is weak and cowardly," Brod said. "But then … little do you know! Beneath that exterior is the power of Superman. Everybody can relate to that, but I believe it is amplified by the Jewish experience."

But it is probably unwise to assign Superman's popularity to any one ethnicity. For though he is so often seen as American, he has largely expanded beyond that now.

When Tye was researching his book, he put out a call for stories about Superman. He wanted people to tell him what he meant to them. He had expected most responses to come from America. But they did not. "They came from Europe and from Africa. From everywhere," Tye said.

In the end, perhaps it does not matter how Snyder directs Man of Steel in 2013. He can take Superman in a darker direction, he can bring out a movie more suited to the arthouse cinemas than the multiplexes. He can make him represent the ominous and confusing world of 2013. But in the end the more he changes the more Superman stays the same.

For Superman is not just some sort of unique being flying high above us. In the projection of our desires, hopes and fears, Superman is us.