It’s the study of Cosmic inflation that led scientists to believe that a Multiverse is a very good possibility. It’s not just an idea. It’s a calculated idea. Physicists have been able to calculate how many possible universes could exist in a Multiverse. Yes, a Multiverse would definitely prove that we are not special. Of course you cannot prove the existence of Multiverse. Maybe if they can discover a Graviton one day, they might be able to detect another universe.
I will see if I can find an interesting read on Multiverse and send it your way.