Up until then, there were lots of teenage superheroes, and they were almost all sidekicks. The appeal of Spiderman was that he provided a wish fulfillment pathway for kids who aspired to be the hero instead. Saving the day instead of getting rescued by an adult.
...Han Solo in astronaut school,
Han Solo wasn't the hero of Star Wars. Luke was. A New Hope is his origin story. Empire is the best film in the franchise, and the second act is Luke at 'Jedi school'.
You don't always need to see a superhero origin, but sometimes they work great.