Some of the characters are very much representatives of conventional types, while others are more fully individualized.
It's fair to say that both pairs of young lovers are cardboard characters; aside from one woman being short and the other tall, their characters are interchangeable, and the same is true for the young men.
Theseus and Hippolyta are less themselves (historical/mythological characters with a specific history) and more a standard upper class/ruling couple.
Many of the elements that are sources of fun in the rude mechanicals are standard stage tropes—the foolishness, the overacting, etc.
The lesser fairies (Peaseblossom, Mustardseed, etc.) are essentially standardized and interchangeable.
Who, then, is an individual, and in what ways? Titania, Oberon, and Puck, in the detailed specificity of their shared history, and Bottom, a bit, for the nature of his extreme egotism.