Some time ago I was trying to come up with a (at least to a degree unique) puzzle for my side-scroller, too, and had to learn that it's very hard to do so.
Take a piece of paper and try to draw a few puzzle sketches first, try to be creative while thinking of more general aspects such as turning and commuting things or combining and disconnecting certain elements. The general or current setting of your level can (and maybe even should) dictate the puzzles in a way, too, check how the material of the objects can influence the former (stones, crystals, metal/ wood, maybe mechanics from a Mayan or sand temple).