I'm about to start a new story and there are a bunch of characters I need to make but I already have four characters created that I don't want to mix up with the new characters. Is there a way to separate them into folders or sections or something??
Yep! Use a new Universe for the new story and assign your characters (and other pages) to that universe. When you do so, only characters (and other pages) will show up in the linking dropdowns (e.g. if Alice and Bob are in one universe and Carol and David are in a second, Alice's dropdowns will only list Bob). You can also click the universe icon in the top-left of any page (in the blue banner up top) to filter out every page other than the ones in the universe you're working in. :)
Oh! I had no idea– thank you so much @andrew (Our Supreme Lord and Overseer) that's so much help :DD