Designated Hero: Jack, an idiot who sells his family's biggest good for a seemingly worthless item, gets lucky when it turns out to be more valuable, then uses it to steal some other guy's stuff even though his wife, who also owns that stuff, was kind to him. Various adaptations have taken their own way in dealing with this. The Disneyadaptation had the harp Jack steals from the giant belong to his town in the first place, so he's taking back his own property. Into the Woods deconstructs the story by having Jack face the consequences of his actions, in the form of the giant's wife coming after him for revenge.
Designated Villain: The giant, a guy defending his home against a persistent thief, and is killed by him. (Of course, he was also going to eat Jack, but wanting his stuff back is perfectly valid.)
Draco in Leather Pants: The giant gets a lot of this. Yes, he wanted back the things Jack stole, that's fair enough. However, many ignore/forget that he's also a murderous cannibal intent on slaughtering and eating Jack the second he catches him. It's even implied his own wife is afraid of him!
Family-Unfriendly Aesop: The moral of the story seems to be that you should totally give away something that has a lot of worth for something that seems worthless, because it'll always pay off by giving you immense wealth.
Or that stealing is the way forward.
There's an animated Fractured Fairy Tale version that openly embraces this trope, portraying Jack's mother as constantly thwarting her son's efforts to enrich them by stealing magical money-making devices from a cruel and magical millionaire, ultimately leaving them both as poor as ever as the narrator openly proclaims honesty and principles are not inherently rewarding.
Ron the Death Eater: Jack gets this as much as the giant gets the Draco treatment. His actions aren't exactly what most today would consider "moral", but all of them, save his foolish bit of gullibility in the beginning, are done out of desperation. He steals from someone who has a wealth of treasure he seems to have no need for (in some versions, he even stole them first) because he's living in poverty in a time where it's much harder to make ends meet as it is, and chops down the beanstalk because the giant was on his way down to kill and eat him. An anti-hero, to be sure, but certainly not the Villain Protagonist many see him as.