Who is Jenny from whirligig?

In the book, Jenny is a teenager who discovers one of Brent's whirligigs in San Diego. According to the story, she lives with her parents and ailing grandmother.
One day, Jenny's grandmother asks Jenny to drive her somewhere. For her part, Jenny is initially reluctant to comply with her grandmother's request. After all, she only has a learner's permit, and neither of her parents are home. Additionally, the only vehicle available to Jenny (and her grandmother) is an old manual Toyota. Jenny knows that she isn't very skilled at driving a car with manual transmission.
However, at her grandmother's insistence, Jenny does her best to steer the car through the streets of San Diego. At this point in the story, it's worth noting that Jenny doesn't know where her grandmother is headed. She does her best to follow her grandmother's directions, however. But, as time passes, Jenny becomes more and more frustrated.
For her part, Jenny's grandmother is determined to visit some landmarks that hold special significance to her. For example, they drive by her (Jenny's grandmother's) old house, which likely reminds the latter of happier days in her life. At last, they reach a two-story house that has a porch "occupied by four rockers." On the porch stands a whale whirligig, with a white triangle for its spray. Atop the spray sits a dark-haired woman.
Jenny's grandmother draws Jenny's attention to the whirligig, effectively telling her that there are still good people in the world. She points out that the person who made the whirligig must have been a good person, because he made the whirligig for everyone to enjoy. Jenny's grandmother advises her not to focus on the Holocaust and men like Hitler who commit evil deeds. She maintains that those who died in the Holocaust would have liked everyone to live life to the fullest. Jenny's grandmother states that she thinks about the good in people when the "bad memories" assail her.
So, Jenny (and her grandmother) are examples of those who have been greatly impacted by Brent's whirligigs.