The Talmud puns on nesi’im, which here means “chieftains” but can at a stretch mean “clouds”. The sages suggest that just as the manna rained down daily for the Israelites in the wilderness providing food, there was a daily delivery of pearls and precious jewels which were needed for the Mishkan, the portable shrine which the Israelites fashioned for God’s spirit to dwell in.
The sages seems to be trying to solve several problems. Most obviously they need to explain how jewels could be obtained in the wilderness.
But they are also saying something about the arts. People do not live by food alone. We need beauty too. And in the way that the human body extracts energy out of food, we are also programmed to take what nature gives and transform it into beautiful things. Freedom will start to pall pretty quickly if there is no outlet for creativity, and so our desert-dwelling ancestors needed materials for crafting alongside deliveries of food.
The Torah spends so much time enumerating the details of the Mishkan, not only to suggest that it was itself important, but also to signal that the process of creating it was, too.
