Is Huck Finn a moral or immoral character based upon his thoughts and actions throughout The Adventures of Huckleberry Finn?

It depends on whether you are looking at the letter of the
law, or the spirit of the law.

By the letter of the law,
Huck does several illegal (and immoral) things. He harbors a run-away slave, he steals
food and supplies, he lies to get out of trouble, and he has nasty habits like smoking
and laziness.

However, Huck's spirit is moral in that he
sees people for who they are and not just as a color or a position in
society.

The best example of this, of course, is the way
Huck is with Jim. Due to his upbringing, Huck does call Jim a N*****, and he struggles
with the idea that helping a slave get free is stealing another person's property, but
he still always sees Jim as a person and a friend.

Whether
they are on an island or floating down the Mississippi on a raft, Huck's conversation
with Jim is free and easy. There is no hierarchy. Huck doesn't demand Jim bow down to
him. Huck even went against his boyhood values by not turning Jim into nearby slave
traders.

Ultimately, Huck even risked hell (which is where
he thought he would go when he didn't write Miss Watson and tell her where Jim was) to
allow Jim his chance at freedom.