Facts of life on the Mississippi
Huckleberry’s father, for example, represents many of the negative aspects of lower-class southern society: he is an abusive alcoholic living in extreme poverty; he is also racist and anti-emancipation, because he (implicitly) knows, that he is really only a step above slaves in the social hierarchy.
Slavery itself is seen as not only a matter of fact, but even as good and right. We can see that Huck, at the beginning of the novel, does not question it and even considers himself a sinner for helping Jim escape.
The chapters dealing with the two rival southern aristocrat families point to a cultural emptiness of “new money” Americans. They, for lack of their own culture, seek to imitate the lifestyle of European nobility such as creating art (poems and portraits) as well as pointless deadly feuds (of course alluding to European tradition with Romeo and Juliet).
Narrative perspective
The use of a teenage narrator could serve to provide the 19th century reader with a fresh, “innocent” perspective on what could be their own lived experience of the south. It serves to point out the problems of greed, slavery or blood feuds. Huckleberry often achieves this simply by asking people simple questions (such as when he inquires about the origin of the feud with Buck).
The book could in a way be seen as a bildungsroman, it could however be questioned if Huckleberry really learns anything given the final chapters, where he reverts back to his old ways under Tom Sawyer’s influence.
Heroes
Huckleberry is a pragmatic character, who questions social conventions that exist only for their own sake, whether it be religion, slavery or the aforementioned feud. He questions religion because it is not useful to him and he questions the validity of slavery, because of his experience with Jim. He creates his own moral code and does not adhere to set ones.
Jim is in many ways still a caricature of a slave: he is superstitious and his lack of intelligence is sometimes played for laughs. The portrayal is, however, very sympathetic and empathetic to his struggle and he is clearly portrayed as a human being with his own voice and agency (of which he is robbed in the final chapters by slavery as well as Tom Sawyer’s games).
The king and the duke are motivated solely by greed and represent the supposed enterprising nature of Americans. Simultaneously their portrayal brings into question the morality of action based solely on profit.
The book also contains “well meaning” slave owners such as the widow. Those people are not seen as inherently evil. The Phelpses even treat Jim fairly well, they do, however, still deprive him of his fundamental right to freedom. Slavery is therefore seen as a system, which is perpetuated not only by explicitly evil people, but also by ignorant people, who simply accept the status quo as it stands.