What is the theme of A Single Shard?

Linda Sue Park's A Single Shard tells the story of a young homeless orphan boy called "Tree-Ear" in twelfth century Korea. He begins working for a perfectionist potter and eventually becomes his apprentice.
The story clearly values hard work, selflessness, honesty, and respect. Tree-Ear eventually gains his goal of becoming Min's apprentice by being hardworking and honest and respecting and helping people despite his own needs. He works hard doing what Min asks of him, even if it is not what Tree-Ear hoped to do. He is honest when he breaks pottery of Min's. He always makes sure to bring food to Crane-man, who has taken care of him, even though it initially diminishes the amount of food Tree-Ear gets; he clearly respects Crane-man and wants to take care of him and give back to him. It is clear that Tree-Ear gains rewards not through being pushy, disrespectful, or selfish but by caring about others, caring about the duty he has to those who have provided for him, and valuing honesty and hard work. Because of this, it seems Park, with A Single Shard, is advocating for this kind of behavior and arguing that life will be better for honest, hardworking, dutiful people.