The original teaser for Star Wars was made before they had John Williams' score:

https://youtu.be/XHk5kCIiGoM?si=VxAJcCATzwn6gZPw

Watching it may help you appreciate just how important the Williams' score was to Star Wars' success. It's one of the all-time greats!

I'd also add that some movies are worth watching purely because of their score. e.g. "Conan the Barbarian" is a pretty shlocky flick. However, the director and composer took a collaborative approach to the score that was closer to opera than film. Unlike most movies, work on the score began before filming and there was continual collaboration during filming. The result remains one of the best scores in the history of film, and a film that makes the music its backbone.