Huck promised Jim he wouldn't tell, and Huck does not break his promises.  In addition, Huck has been told to oppose abolition when that might not be his actual opinion.  Huck is also very lonely when he is by himself.  Jim is Huck's company and keeps him sane.  This tells the reader that Huck can not be alone, and he is a trustworthy person.  Also, it shows that Huck has been told what to think about slavery.

It shows what was important during that time.  People found it more important to find an escaped slave who has a slight chance of being the murderer rather than find the drunk who most likely killed Huck.  Slaves were very important to the people of this time.  If a slave ran away, a massive search party is sent out.  When Pap disappears, no one goes looking for him.

At the beginning of the chapter, Huck does not believe in superstition.  Huck and Jim had very good luck up to that point.  They found the house, the cavern, and eight dollars in silver.  When the snake bit Jim, Huck started to believe in superstition.  The bite was caused by Huck touching a snake skin.  Huck believes in more superstition at the end of chapter 10.