Instead of imitating other people, we ough to be our own selves. In what ways does star girl shows her true self? How do people react to these instances? Why?

In a way, both her name, and her act of naming herself tell us that Stargirl is a free spirit. She won't be defined by any name that another person might give her, and when she chooses her name, it's just kooky enough, and just profound enough, to reveal her true self to those around her.

Explanation:

Stargirl is compassionate beyond measure. The girl sends thoughtful gifts anonymously to unsuspecting people just to be kind. She cheers when a kid on the other team makes a basket. She attends the funeral of a stranger. Stargirl doesn't just make a halfhearted effort to spread love to the world; she really engages with people on a deep level. She seems to feel both the world's collective pain and its joy and takes active measures to connect with people in both situations. Sadly, many of her efforts only create anger and resentment at her school, isolating her from the very people she cheers on. Which brings us to another unique personality characteristic of Stargirl:

She really and truly doesn't seem to care what people (collectively) think about her quirkiness. Lots of people lay claim to this feeling, but as a whole, people dress and act a certain way because society and/or the group they long to be a part of have particular expectations for these behaviors. Stargirl dresses as she wants. She befriends whom she wants. She doesn't seem to care about the expected social norms at her high school.