When you need to create a story world, your existing characters already know how it works so it will look phony if characters tell each other something that they should know, such as one character saying, “As you know, this is a world where magic can be wielded by wizards.” The best way to avoid such clumsy exposition is to make your story’s hero a complete novice to this story world. That way the hero learns about this story world at the same time as the rest of us.
In “Fury,” the hero is a raw Army soldier who’s assigned to a veteran tank crew. The tank crew already knows what to expect from war, but we (and the hero) don’t, so the hero becomes our introduction to how an American tank crew deals with fighting Nazi soldiers.
In “Avatar,” the scientists and soldiers already know what the alien world is like, but we (and the hero) don’t. So as the hero learns how the aliens live, we do too. Even in an ordinary setting such as law school in “Legally Blonde,” we don’t know the world of Ivy League law school and neither does the hero. So as she learns, we do too.
The important point is that the hero only learns what’s important and relevant to the story and nothing more. In “Avatar,” there’s no reason for us to know why the islands float in the sky. We just need to see them to realize we’re in another world, but we don’t need to learn the physics behind these other worldly sights. By staying focused only on information relevant to the story, you can create an amazing new world (like in “Avatar”) without getting bogged down in describing and explaining everything.
The hero always sees the world through innocent eyes, which allows the audience to see that same world through similar innocent eyes. Make your hero naive about the world around him or her so the audience can relate to the hero.
What happens if you make the hero knowledgeable about the world? Then the hero has no reason to explain how the story world works, and the audience will get lost. If you make a knowledgable hero explain how the story world works, it comes across as fake and slows your story down.
So make your hero innocent and naive. Your audience sees the story world through the hero’s innocent eyes and that bonds the audience closer to the hero in the process.