Ironically Casablanca was produced as a b-movie and marks the hight of the studio system. It didn't have a huge budget and it was rushed out to coincide with the allied invasion of North Africa.
We watched it recently after decades of hearing how great a film it was.. it was a superficial letdown instead.
It invented a lot of common cliches and tropes that are frequently used in other movies so in many ways it's a victim of its own success. For example in Star Wars the planet of Tatooine is Casablanca and the Cantina is Rick's Cafe.
Full of cliches, right?
(/s -- victim of its own success...)
Yep. I've joked a fair amount that watching Casablanca now is very likely to make you think "this is full of clichés" until you realize, "wait, this is where all these clichés actually started, isn't it?"
Similar to attending a play from The Repertory and hearing all the quotes that originate from it. Especially Shakespeare. But also the rest of the usual suspects. I'm shocked (Shocked!) to learn that movies borrow from Casablanca or Shakespeare.