What makes Dickens's characters so memorable?

Dickens's greatest talent was in having a seemingly inexhaustible ability to create striking and memorable characters. He does this in many of his novels, but nowhere as bountifully as in Great Expectations. Mr. Jaggers is a lawyer's lawyer. He cares nothing about the spirit of the law but only about the letter of the law and making money. Miss Havisham is the quintessential poor-old-lady who feels sorry for herself and blames everybody in the world for her unhappiness. Estella as a young girl is the quintessential spoiled, snobbish little rich girl who is proud of her grace and beauty. Joe Gargary is the honest working man who helps hold up one of the four corners of the world. His wife is the scold we have all known, a female bully who enjoys making trouble. Abel Magwitch is such a powerful figure that he has to be kept offstage much of the time in order to prevent him from overshadowing everybody else.
One feels that Dickens could invent many more characters to fit into any slots where they were needed, and that he could make all these characters equally credible and viable. The author's trick, it would seem, was to take common types, exaggerate certain of their traits, and present them as individuals. That way we feel we have known them all our lives. He could do this more easily by presenting them through the point of view of Pip, a very young man who knows nothing about the real world, and to whom everything and everyone is new.
With Pip, readers feel that his mind is like a fresh new photographic plate which can take in-depth pictures in a flash. He is not judgmental in his boyhood but becomes so with age and experience. We notice the sharp contrast between his impressions of Mr. Jaggers and Miss Havisham when he is a little boy and his impressions of the same people when he has reached maturity. They have grown smaller. They haven't changed, but he has.