For the small period of time Huck lives with the grangerfords, he seems "normal", largely due in part to the fact that he is around reliable adults and people his age that live under reliable adults in a nuclear household (opposite of Tom). It's almost as if the lack of normal socialization in his life and the "freedom" he has is his biggest constraint in terms of direction and thinking in life because he has no one reliable that acts like a normal person(cross Ms. Watson and her sis, Pap, and Tom off of that list).

Everyone Huck spends time around is either narrow minded, delusional, or of poor moral character(usually all three of these characteristics are grouped or paired with one another, as they are in the characters that Huck spends much of his time with). The person who Huck seems to like isn't even able to be an intentional or unintentional role model or guiding figure(yet) for him because he is a black male in a society with a slaved based agricultural/economic system, something Huck is conscious of(Jim's label). This stigma within the society as a whole is something that Huck has not yet taken down from a point of validation although he displays some feelings, thoughts, and actions that are often against the grain. I think it is important to note that the empathy and change of heart that Huck is capable of is partially due to his lowly position in society and the unsystematic life that he leads.

 Most people you come across are sheep. You are probably one and you might not even realize it, saying, "I'm not like them, I'm not like those people. I'm different".

Yea right.

Sherburn's speech on human nature highlights a very basic but common problem in the actions of people in this 1830's society, those before it, and those after it- the mob mentality. The sheep conversation is one for another post or medium, but it is easily comparable to slavery. People aren't really questioning what they are doing. Of course the (probably not)near lynching occurrence is different from slavery in a number of ways(resistance, incentives, etc.). Huck is one who in this limited way, not adopting a mob mentality. This might be normal for human beings, but in the abstract, nuanced(although not impossible to understand at a decent level), following the heard becomes dangerous(especially when you think you're leading your own way or aren't away you are being hearded, sheered and butchered for resources(sounds nice right)). Not only is it/will it be for the mob, but anyone outside of the mob who gets used as an animal for labor(slaves here). When no-crap-taking shurburn speaks if human nature, he speaks of an all well to known human constraint.

(2 Constraints pictured above is a less lazy(peep earnings) and more comfy(peep pillow and plush animal shoes that were made but some person in a factory who gets paid sh☺t) sheep.)