is spider Man an avenger?
What universe a character exists in depends on what corporation acquires their franchise as a subsidiary. The multiverse has less to do with theoretical astrophysics than it does equity ecosystem where one entertainment and media conglomerate engulfs another. When either Paramount+ or Prive or Disney absorb one or the other, who knows what crossovers will be. They might put Spider-Man in a Borg Cube or on the Death Star.