For an interesting starting point for analysis, notice that Jemmy's given name is Gemstone Opal Stott. Her name is a hint that secretly, she's worth so much as a person, but because of her difficult, broken family life, and because of the way racism shapes her experience of public school, she never realizes that her identity is beautiful or a thing to be cherished. She doesn't understand the beauty of her own identity, even though it's built into her name.
That's why it's so important that she meets Otis Chapman in the novel, because her participation with art opens her eyes in two ways: Firstly, it opens her eyes to art itself. Suddenly she realizes that she could be expressing herself through the visual arts, and she finds a new passion for life. Secondly, Otis asks her to model, so she is put in a place where someone else is going to treasure her identity by immortalizing it in their artwork. In other words, Otis treats her as if she is valuable, so while she's sitting modeling for the mural, she feels beautiful and important.
Contrast that with the way she felt about herself before. When her father pulls her out of school to get a job (so that he can stay drunk and lazy), she goes along, not concerned about what she might be given up by dropping out. Is that because she hates learning? No, it's a reflection of her experience of school, and it is a reflection of her sense of self and the role she believes she has to fill. When she becomes passionate about art, she takes a huge step toward adult independence.
