"En taro adun," said the Zealot.
While it may seem to many that the Overlord is smarter than the Zealot, there is no evidence to support this claim. On the contrary, the Zealot, as part of the Khala, may have access to infinities of energy that the Overlord only dreams of. It satisfies our lust for sci-fi that the Zerg are the more formidable of the alien races, but it doesn't make much sense metaphorically. The Protoss are a superior race, like an effervescent transformation, a personification of the mind that makes a Zerg work. Where everything with Zerg is physical, real, the aspects of a Protoss's higher consciousness are like those of a human. The Protoss mind is a visceral collective, a spatial topography of consciousness like a heliographed artifact chiseled on the face of the world itself. Unlike the Zerg, whose submersion of the higher planes is evidenced in their insectoid hierarchy, the Protoss are beings of hylomorphic properties (as we see in the Dragoon). It is as though for every Protoss there are two Protoss, the physical manifestation and the living, breathing soul. Only the Protoss are like this, with their close Terran counterparts (the Ghost and the Wraith).