The riddle is wrongly considered a “lesser” or “lighter” kind of verse (“light” verse is implicitly considered “lesser” poetry, in contemporary literary convention). The riddle, in fact, is at once playful and profoundly religious. Consider how it enjoyed its heydey in medieval times. In Latin after Constantine through Old English, you find the best poets writing riddles.
This relates to what Dostoevsky’s Ivan describes in “The Grand Inquisitor” as the threefold origin of unified religious belief (certainly one of the central fixations of the medieval mind). Miracle, Mystery, and Authority.
The riddle’s own form, verse—the spoken act of music, alliterative, caesura’d, rhymed—is the riddle’s Miracle. The riddle itself is all Mystery, by nature. What am I? The perennial riddle-question lies at the origin of the human. The riddle’s Authority lies in its knowing something the reader doesn’t, and giving hints about it. The riddle is the lightest of heavy forms. The riddle is a sign and wonder pointing to itself.