Calpurnia, Scout and Jem Finch's nanny, has been criticized as fitting the "mammy" stereotype of a matronly black caretaker who is safe in her non-sexuality. Tom Robinson, who happily lends his services to a young white woman despite having his own family to feed, has been compared with the "contented slave" archetype. The other black characters have only superficial roles – i.e. being a grief-stricken community and treating Atticus as their white savior. The only real exception to this rule is Lula, who angrily turns the Finch children out of her black church (only to be hushed by the other church-goers).
There are several reasons why the novel might suffer this apparent oversight, the most obvious of which being that To Kill a Mockingbird was written by a white woman in the late 1950's. (With all due respect to Harper Lee, it's nearly impossible for even well-intentioned people to transcend the attitudes of their place and time in society.)
Then again, it's possible that the novel intentionally gives us a limited perspective on African Americans in order to illustrate a point: since blacks lived on the absolute periphery of society in 1930's Alabama, a story told from the perspective of an average white person should reflect this in both its narrative structure and content.
In this story's case, all the black To Kill a Mockingbird characters (except the nanny) appear when tragedy strikes their community and disappear just as quickly when that plotline ends.
Before we get too technical in our analysis, we should also keep in mind that the story unfolds around the experiences of a six-year-old white girl; expecting real insight into the black