Hogwarts headcanon time:
Everyone seems to think that all the hidden corridors and moving staircases are intentional, because the founders were a bit insane (which is true). But what if most of it wasn’t intentional? What if it’s the cumulative result of generations of young witches and wizards learning magic and all the stray magic floating about?
Like, what if that one stair poor Neville keeps getting stuck in was the result of someone trying to pull a prank on their friend in 1824 and no one could figure out a counter curse? Or the moving staircases were the result of too many jinxes and missed spells and no one really knows why they move or when they started (but Hermione did find the first recorded instance of a moving staircase in 1532 in Hogwarts, a History)
I feel like all those quirks in the castle are much more the result of the school just being so saturated with magic and mischief that it’ll never be a remotely normal building again.