An alliance broken at Sinai

The biblical shift from the ministry of the first-born to the ministry of the priestly caste was more than just a technical restructuring; it was a political act: it removed the divine presence from the government of the people and instituted safeguards as a restraint on the government of the people.

Qadesh li kol bekhor was the expression of an alliance between YHWH and the Israelite ruling class. That alliance was broken at Sinai with the shattering of the first tablets. The ruling structure that replaced that alliance moved the definition of consecrated rule from the first-born to Aharon's sons. The kohanim would not even pretend to be rulers of Israel's sons. They were YHWH's ministers whose primary function was to mitigate the most extreme outbreaks of the exercise of power, be it from YHWH or from Israel's ruling class.