What might be Gardner's message in juxtaposing the beautiful stories the Shaper tells of human nobility with Grendel's discovery of the murdered body near where the youths make romance in the leaves?

There is a disconnect here for Grendel. Humans are a paradox. Grendel tends to see things in black and white, good and evil. Can humans be good and evil at the same time? Grendel can't understand this dichotomy.