Suggestions:

1. The shape of the outer perimeter of this glyph is delineates the full moon.

2. Inside there are two signs. The one at the bottom shows the end of the period of Waxing Moon (left) and the beginning of the period of the Waning Moon (right). At full moon the light is at its maximum and incline is exchanged for decline.

Idea:

The sign similar to a sitting person perhaps is indicating somebody eating. At a night with full moon there should be feasting.