What's your world building headcanons?
People in the HP subreddits love to point out that others completely overthink the details of a world that was never meant to be that deep. It's meant to be a whimsical world to ignite the imaginations of kids. In the fanfiction world, we need to fill in the holes, and smooth out the rough edges of the setting to have it make sense and have a sense of structure for our stories. Whether it's something you came up with for your stories, or something you read that resonated with you, what's your headcanons?
Mine is that Hogwarts isn't the only magical school in the UK. It's the premier elite school in the UK. It's the exclusive school for the social elites and the gifted kids. When you look at all the kids, they're a who's who of prominent wizarding families. They're the kids from the sacred 28 families and the families that should have been on the list, had the author not snubbed them because he hated them.
Or they're kids with extraordinary potential. Harry was told that the patronus charm was advanced powerful magic that trained adults had trouble figuring out. Ministry officials were absolutely amazed that a kid his age had pulled it off during his O.W.L. exams. Meanwhile, he gathered up a random sample of his fellow students and taught them how to do it within a couple weeks. These kids aren't your bog standard high school kids. They're the exceptional stand outs.