So many of our modern pop culture stories are about good vs. evil in that every character must pick a side, and we know that one side is right and the other is wrong, and we are supposed to root for good over evil. In Star Wars, these two factions are explicitly named, to shape our expectations and label who we are to identify with. It doesn't always work as intended, since while Darth Vader may be evil, you have to admit his menace is thrillingly cool. The dichotomy of good guys and bad guys is clear in superhero movies, Westerns, murder mysteries, horror, fantasy, and even history books ...is there any doubt that World War II reads like a morality tale? But it wasn't always that way.
Stories from an oral tradition never have anything like a modern good guy or bad guy in them, despite their reputation for being moralising. In stories such as Jack and the Beanstalk or Sleeping Beauty, just who is the good guy? Jack is the protagonist we’re meant to root for, yet he has no ethical justification for stealing the giant’s things. Does Sleeping Beauty care about goodness? Does anyone fight crime? Even tales that can be made to seem like they are about good versus evil, such as the story of Cinderella, do not hinge on so simple a moral dichotomy. In traditional oral versions, Cinderella merely needs to be beautiful to make the story work. In the Three Little Pigs, neither pigs nor wolf deploy tactics that the other side wouldn’t stoop to. It’s just a question of who gets dinner first, not good versus evil.
The situation is more complex in epics such as The Iliad, which does have two ‘teams’, as well as characters who wrestle with moral meanings. But the teams don’t represent the clash of two sets of values in the same way that modern good guys and bad guys do. Neither Achilles nor Hector stands for values that the other side cannot abide, nor are they fighting to protect the world from the other team. They don’t symbolise anything but themselves and, though they talk about war often, they never cite their values as the reason to fight the good fight. The ostensibly moral face-off between good and evil is a recent invention that evolved in concert with modern nationalism – and, ultimately, it gives voice to a political vision not an ethical one.
The shift to battles of morality only began a couple hundred years ago. Robin Hood had been around a long time, but didn't rob the rich and give to the poor until 1795. Grimm's Fairy Tales added some morality to old folk stories soon after. Read about the rise of the good guy trope at Pocket.