The students in my film class about a decade younger than me have a hard time with the class politics in The Hidden Fortress. They especially stumbled over the two peasant characters

They were confused by how "dumb" they seemed and had trouble understanding what Kurosawa was trying to say. But Kurosawa was very much part of and influenced by the japanese caste system (later filmmakers like Oshima would criticize him for this)

If the peasants are dumb and lacking in bravery, that's because that's how Kurosawa viewed the peasant caste. It wasn't even a negative. That's just how their class would be. They can't outshine the samurai or ruling class in intellect or bravery.

Kurosawa was descended from a samurai lineage, raised in imperial japan before all that got really upended up post-WW2. He was pretty high up the class totem pole. That's going to paint your worldview

(A lot of the breaking of traditional class structure had started with the Meiji Restoration but those classes were still pretty well in place until post ww2)