The innocence of the boy trying to do the right thing hints that he is the only morally corrupt character in this downcast movie. Although his social structures seem impact considering the circumstances, he takes the attacks of his grown-up peers and family way too seriously. The collection of characters he deals with resonated strongly with me: the strict father, the guilty brother and the sister trying to avoid prostitution. Maybe the elder brother could have been portrayed a little better, as I think that the surgeon in "Die Mörder sind unter uns" portrays the ambivalent nature of guilt better.
Although the ending is sad (and the scene very memorable) the film didn't feel too negative. There is an element of sacrifice of purity in the ending. If taken as an allegory, the danger is still lurking within the ruins (the teacher and his "boss") and although hidden away, it is powerful and financially potent.