Social classes are the great lines that divide us. And in the world of Harry Potterand the Chamber of Secrets there are all sorts of dividing lines. People can be rich or poor, servant or master, pure-blood or Muggle-born, famous or adoring fan. But these are all just categories and Harry and his friends learn pretty quickly that they don't tell us anything about people.
A person can be a total jerk and be in all the "right" categories. Or someone can be the kindest, most generous creature in the world, but be born a slave. Harry is all for getting rid of these divisions. But doing that will take a lot more than the wave of a wand.
Questions About Society & Class
Why is Lockhart so obsessed with being seen as a famous person by society while Harry doesn't care about being famous at all?
How does Hermione know what "Mudblood" means and Harry doesn't? Do you think she's been called this before?
Why are the Weasleys considered a disgrace to the wizarding world by the Malfoys? How do the Malfoys disgrace wizards everywhere through their actions, too?
Chew on This
The pure-blood wizard's belief in his or her own superiority mirrors racial and ethnic conflicts in our own world.
Harry doesn't treat Dobby like a servant because he doesn't know Dobby is a servant. Just like he doesn't think of Hermione as a Muggle-born because he doesn't realize this is a big deal. Harry didn't grow up in the wizarding world so he never learned about its prejudices or class distinctions.