There are plenty of characters that aren't still under copyright. Sherlock Holmes, Norse and Greek Mythological heroes, Winnie the Pooh (now), most of the fairy

There are plenty of characters that aren't still under copyright. Sherlock Holmes, Norse and Greek Mythological heroes, Winnie the Pooh (now), most of the fairy tale stories (which Disney used early on) and a huge number of other characters and stories. You are focusing on the small number of popular franchises that are popular because people are creating new content instead of the huge number of stories that are there just waiting for someone to make a movie, video game, etc.