Last time, we discussed the old woman known as Mombi and mentioned that she had a boy named Tip living with her who didn't like her.
While Mombi was out one day, Tip decided to frighten her with a jack-o-lantern, but instead of making it into a lantern, Tip made a wooden body for it and dressed it with some old clothes he found in Mombi's house. Setting it up in the road, he dubbed it "Jack Pumpkinhead."
Arriving home, Mombi noticed the pumpkinhead and greeted it, thinking it to be a farmer. She was shocked when she realized her mistake, but then she grew angry, and was about to break the pumpkinhead, when she remembered that she had the Powder of Life with her. She used it to bring Jack to life, and then intended that he would work for her when she made Tip into a marble statue.
Jack, having a surprisingly good basic vocabulary at his "birth," never considered himself a good thinker. He recognizes that his head is a pumpkin and pumpkins are not known for his wisdom, so he quickly looks to others for advice and guidance. This open humility makes his personality is mild and endearing.
When the Sawhorse runs away from Tip with Jack on his back, Jack arrives in the Emerald City and makes a fast friend in the Scarecrow, who recognizes him as being worthy of his friendship, even though Jack's misunderstanding and foolish suggestion that he must speak a different language than the Scarecrow led to an embarrassing trick performed by Jellia Jamb.
Surprisingly, Jack has something different from most other Oz characters: Baum originally intended that Jack perished sometime after the events of The Marvelous Land of Oz. In the final pages, Baum writes:
Jack Pumpkinhead remained with Ozma to the end of his days; and he did not spoil as soon as he had feared, although he always remained as stupid as ever.Aside from the Queer Visitors from the Marvelous Land of Oz stories (which may or may not be canonical, depending on your personal view), Jack doesn't reappear in Ozma of Oz or Dorothy and the Wizard in Oz, though Neill did include him in some illustrations.
Aside from visiting the Emerald City or people visiting him, this is very much where Jack stays throughout the rest of Baum's books, with the exception of the Little Wizard story "Jack Pumpkinhead and the Sawhorse" in which the two go to rescue children lost in a forest, Jack's head getting destroyed in the process, but the Wizard arrives with a fresh head for Jack. The Emerald City of Oz reveals that Jack designed the Scarecrow's corncob mansion.
Ruth Plumly Thompson gave Jack a book in Jack Pumpkinhead in Oz, where he travels with Peter around several small kingdoms in the Winkie Country. It is, in fact, Jack who meets the Red Jinn—later named Jinnicky—before any of the other of the classic Oz characters. Jinnicky gives Jack advice on how to save the day thanks to Jack thinking of using the Jinn's dinner bell to his advantage.
John R. Neill gave Jack starring roles in The Wonder City of Oz, in which he has a (second?) home in a decommissioned Ozoplane in the Emerald City and runs a symphony; and The Runaway in Oz, in which he accompanies Jenny Jump and the Woggle-Bug on their search for the Patchwork Girl.
Thanks to Jack's humble but agreeable personality, he's one of the more popular Oz characters and a great friend!