“Training” isn’t everything. Listen to a couple of hours of John Williams scores in a concert setting (https://www.bbc.co.uk/events/enfmbp/play/ap33v2/b08y02bl) and you might come to the same conclusion as I did - he’s only ever written one piece of music, but he’s very good at making variations on it.
Classically trained - yes of course (Juilliard etc). But comparing Williams’ music with the “great” 19th century romantic composers, as some of his more gushing admirers do - “you cannot be serious” IMO.
(Actually, if I had the money to risk losing, I would sue him for copyright violation over the “Jaws” theme - I wrote the soundtrack for a movie shot on 16mm film back in the 1960s which won an award at a Cannes Amateur Film Festival and uses the exact same musical idea, so there wouldn’t be much dispute about my evidence at least - it’s right there on my soundtrack!) That’s stealing from a teenager still in the UK equivalent of high school!!!