Characterized as brave, a boy with a lack of fear, full of strength. He's a 100% hero with no superpowers. Although his intentions are not that good, as he uses the giant's wife's kindness to his advantage (she gives him dinner and hides him from the ogre) we believe he's only trying to survive in the cruel world. Jack often takes other people's kindness for granted and instead of earning the money legally (although we can see his mother discouraging him from looking for a job) the ogre's wife closes her eyes to Jack's robbery and he doesn't even thank her. He uses the ogre's wife as his pawn in his crime and doesn't have any intentions of apologizing, proving he's nothing more than a con man and has no guilt or feeling about his crime.
When he gets what he wants he cuts the beanstalk and kills the ogre in order to cover up his crime. Without regret or fear about murder or theft, Jack happily keeps stolen things to himself and has no shame in hurting others.
A complete opposite of Jack. She usually stays home while Jack goes out to the market and adventures. She mocked him when he attempted being a grown-up (when he says he'll go to the market to sell their cow) and prove he can be a provider for the family. She's the only real female character and contrast to him so while Jack is somewhat heroic and active she is passive, stays home crying and fearing for his safety.
The author states that Jack's mother is a poor widow, but why is she a widow? Tabart's version has one part where Jack tells the ogre's wife about his heroic and noble father who got killed by an ogre when he was three months old. Even though the story of Joseph Jacobs doesn't state what happened to Jack's father we like to make a connection and believe this applies to this story giving the tale a meaning and why his mother is weeping all the time - she's afraid she will lose her son the same way as she lost her husband.
The main antagonist is characterized as an oversized fool, with benign and a silly grin on his face. He eats little boys and humans, even though he has a human wife he obviously didn't eat. Although he is enormous in size, he never managed to outwit a small boy Jack.