What is the importance of introducing the boss, Curley, and Curley's wife?

Curley is the boss's son, and because his father only appears once, Curley is the main representative in the novella of the land-owning class. ... When this revenge plan fails and he loses face, Curley picks a fight with the vulnerable Lennie to reassert his status.

Explanation:

in our power to make a world happy - to teach mankind the art of being so - to a character hitherto unknown - and to have, as it were, a new creation intrusted to our hands, are honors that command reflection, and can neither be too highly estimated,