Is that WHY he used newspaper articles and Henry Mayhew's books ( LONDON'S UNDERWORLD and MAYHEW'S LONDON ) as basis for many characters, as well as his fictionalized own life for his novels?
You might just as well then claim that Dominick Dunne's books weren't "realistic".
What about Dickens' best friend, Wilkie Collins' works? Are you going to tell me that his characters weren't just as "diverse", if not more so?
Dickens was not a realist in the Literary sense of the word. Realism was Howells and Twain. I’ve read “The Woman in White” and “The Moonstone” both are wonderful but they are the only two Collins works still read with regularity.