Lots to pick up on here.
First, I agree the 1950s are rather under-represented, but as you say, tough choices had to be made, and this is a list of personal favourites.
Seven Brides for Seven Brothers is terrific, despite the dubious origins, agreed. And all the other musicals from that era you mention are great too.
I think The Court Jester could qualify, but now you have me on a Danny Kaye tangent. I’d have to go with Hans Christian Anderson as his best musical. As a film, it’s fairly middling, but the fantastic songs elevate it way beyond that. My favourite Danny Kaye film overall is The Secret Life of Walter Mitty, though I also have a spot spot for Wonder Man.
Duck Soup is my favourite Marx Brothers film. As for Everyone Says I Love You, I’m really annoyed with myself for leaving that out. I meant to include it and somehow forgot. It’s one of my favourite Woody Allen films.