Fairy tales take a very Zen approach to characterization: lots of the characters simply are. Cinderella is good and pious; her stepsisters are nasty pieces of work. The prince who rescues Brier Rose is brave and persistent. If they've got internal struggles or evolving feelings about an issue, we generally don't see those. We just see the characters be. Ommmm.
Since a lot of characters are one-dimensional in fairy tales, what they do tells us a fair bit about who they are. When youngest sons show mercy to animals in the forest, we know they'll be nice dudes in general. When young women do all the chores they're assigned to, we understand that they're patient and loyal and all that good stuff, too.
When fairy-tale characters get names at all (we imagine there's a lot of "Hey you! Not, not you…yeah, you!" going on), they tend to be simple and descriptive of either internal or external traits. For instance, there are a handful of tales in which the protagonist is named Simpleton. Usually this means he's a nice guy but not so big in the brains department. Of the physically descriptive names, King Thrushbeard bears that nickname for his crooked chin, and Thumbling is, obviously, thumb-sized. You get the idea.
If we had a dollar for every time a character was referred to by status ("the princess," "a king," "that peasant"), then we'd be able to order a lot of pizzas. With fancy toppings.