How does Huckleberry Finn mature due to the various hardships he experiences?

Huckleberry Finn's various adventures take place during a period of transition for him. He's at an age where he's caught uneasily between childhood innocence and the harshness of the adult world. Although forced to mature too early, he still retains that childlike state of wonder and adventure that help make his escapades so compelling.
Life has been hard for Huck. Abandoned at a young age by a violent, drunken father, he's had to eke out a living off the land, relying on his wits to get by. In his childhood, Huck goes through things that most of us would never experience, or never hope to, at any rate. But what doesn't kill you makes you stronger, and Huck quickly develops that whip smart personality of his, giving him the ability to survive in a harsh, unforgiving environment that would be the death of most adults.
The various hardships Huck has endured have made him self-reliant, so much so that he cannot imagine living a regular "civilized" life back in town. He tries, reluctantly, after the Widow Douglas takes him under her wing, but he just can't. Though still outwardly a boy, Huck's experiences have already made him enough of a man for him to feel tied-down by the home comforts of a respectable upbringing.
Huck's lack of civilization helps him to gain a much broader perspective on things, to be able to see the petty foibles and faults of folks who've been raised in the conventional manner. Huck's natural existence, out there in the forests and floating down a raft on the Mississippi, has given him a valuable insight into how people behave, and how complicated, cruel, and foolish they can be.
It's Huck who brings his untutored folk wisdom to bear on the seemingly pointless, bloody feud between the Grangerfords and the Shepherdsons. These are wealthy, God-fearing people, civilized people, so-called. Yet they've been at each other's throats for years and no one quite knows why. Huck's incredulity at the feud and the violence and death it entails provides much-needed wisdom and maturity when those around him appear to have none.
Huck's various hardships also provide him with a much more mature attitude towards money than most adults. Despite sharing $6,000 in reward money with Tom Sawyer, he understands that sometimes money can be more trouble than it's worth. And his shrewdness is confirmed when Pap Finn crawls out of the woodwork to try and get his greedy hands on his son's reward money.