According to eNotes encyclopedia, an picaresque novel is:
Early form of the novel, usually a first-person narrative, relating the episodic adventures of a rogue or lowborn adventurer (Spanish, pícaro). The hero drifts from place to place and from one social milieu to another in an effort to survive. The genre originated in Spain and had its prototype in Mateo Alemán's Guzmán de Alfarache (1599). It appeared in various European literatures until the mid-18th century, when the growth of the realistic novel led to its decline. Because of the opportunities for satire they present, picaresque elements enriched many later novels, such as Nikolay Gogol's Dead Souls (1842), Mark Twain's Huckleberry Finn (1884), and Thomas Mann's Confessions of Felix Krull (1954).
Based on this definition, we must agree that Huck Finn is told from the first person narrative of the title character, who is a low-born boy, and who does move from point to point and social group to social group in order to survive. The novel is a vehicle for Twain's satirical treatment of the issues of freedom, the supernatural, religion, education, politics, slavery, and many others. During his epic journey, Huck also grows up and learns much about himself and his capacity to befriend a black man despite his upbringing and beliefs. He makes the right choices, and while he is not formally educated, he proves that he is not stupid.