What are some negative traits of Jiro?

The protagonist of Katherine Paterson's novel The Master Puppeteer is a thirteen-year-old boy who runs away to a theater in order to learn the art of making stage puppets. However, Jiro is a clumsy adolescent and, at first, makes mistakes as an apprentice.
The master puppeteer's son, Kinshi, is tasked with teaching Jiro the art of crafting and painting puppets. Very early on, we see the distinction between Jiro and Kinshi. The latter is skilled at what he does and is patient with Jiro whilst teaching him. However, Kinshi has difficulty pleasing his father and is sometimes beaten with a bamboo stick for minor transgressions.
Jiro, on the other hand, is a hard worker, but he seems to forget about those who helped him during his apprenticeship. He does not do this on purpose, but the reader is made to ponder whether Jiro should be obligated to return favors to Kinshi and the others who helped him before his success. Jiro also develops a competitive nature the more apprentices he beats on his way to the top.