What does is a major symbol in 'Bumblebee Flies Anyway"?

The central symbol in the novel is its title, an allusion to the bumblebee, which is not supposed to fly because "its body is too heavy and it's the wrong shape." Yet the bumblebee, defying the laws of aerodynamics, flies anyway. In addition to flying, it also "manages to make a little honey every day." Like the little MG Barney finds in the junkyard, "it wasn't built to be driven," yet Barney and Mazzo drive it anyway. Ultimately, the bumblebee and the MG symbolize the lives of the boys, diseased bodies at death's door that are not supposed to think about living; yet the boys do. They even manage to find and share a little happiness among themselves.