Huck is an intelligent, thoughtful, and resourceful boy who is about thirteen as the novel opens. Because of his life circumstances, he has had to live by wits, which has made him practical, quick-thinking, and observant.
What has most formed Huck is his outsider status. A person who has lived his life largely on the fringes of respectable white society in St. Petersburg, Missouri, he is an amalgam of any number of superstitious ideas, real facts, practical know-how, and a shrewd, if usually innocent, ability to assess a situation. Both the comedy and the pathos in the novel arise from his tendency to think and process situations in his own way.
Because of his outsider status, Huck is able to assess people based on how they behave rather than on their social status. He has imbibed his society's racism, for example, but not enough to prevent him from traveling with Jim, seeing the genuine human worth in him, and learning to love this friend and father figure. Likewise, without the intellectual background to assess the ridiculous claims of the Duke and King, he is able to quickly discern their dangerous, sociopathic natures and take precautions.
Huck is likewise quick to discern the cultural and religious hypocrisy of the feuding Grangerfords and Shepherdsons. His lack of pretension, goodhearted nature, and frank appraisals of reality make him an endearing and enduring character.