What is the key lesson or moral that the reader learns from the book Cinder by Marissa Meyer?

The novel Cinder has numerous overlapping themes. Each reader can decide if the author’s primary purpose is to communicate a moral. Cinder, although a cyborg, has the emotions of a human being and she tries to do good in the world. She only learns late in the novel that she is actually a princess.
Two ideas related to this revelation are that the impossibility of escaping one’s destiny and the importance of being true to oneself. Cinder, before learning she is Selene, is forced to become a test subject in the search for a cure for the plague. Even though she had no choice in this matter, she wants to help Peony. While she is attracted to Prince Kai, she rejects his offer so that he will be spared the company of a cyborg. Her behavior is totally ethical, and it seems her destiny was to learn she is actually the princess.