How does Jim fit into the overall theme of The Adventures of Huckleberry Finn?

Along with Huck, Jim is the other major character in The Adventures of Huckleberry Finn and one of the most controversial figures in American literature.

In the beginning of the novel, Jim is depicted as simple and trusting, to the point of gullibility. These qualities are not altered during the course of the novel; instead, they are fleshed out and prove to be positives instead of negatives. Jim's simple nature becomes common sense, and he constantly chooses the right path for him and Huck to follow. For example, when Huck and Jim are on Jackson's Island, Jim observes the nervous actions of birds and predicts that it will rain. Jim's prediction comes true as a huge storm comes upon the island. The moment is an important one, for it establishes Jim as an authority figure and readers recognize his experience and intelligence.

Jim's actions, no doubt, are partly a result of his inability to distance himself from the society in which he has been conditioned. His existence has been permeated by social and legal laws that require him to place another race above his own, regardless of the consequences. But as with Huck, Jim is willing to sacrifice his life for his friends. There are countless opportunities for Jim to leave Huck during the tale, yet he remains by Huck's side so the two of them can escape together. Moreover, when Jim has the chance to be free at the end of the novel, he stays by Tom Sawyer's side, another example of his loyalty. Jim's logic, compassion, intelligence, and above all, his loyalty toward Huck, Tom, and his own family, establish him as a heroic figure.