The clue is in the name: the person who owns the "copyright" is the one who has the right to copy it. This has been the case since the Licensing of the Press Act of 1662, so we shouldn't be shocked by it.

You can't transfer ownership of the IP to the Avengers Movie, because only one person or entity at a time can own it. That's why for example, we license software as developers, instead of selling it to the end user.