P changes or duplicates JE narrative by using his own terminology. On a close look at some of P's narratives concerning Moses, we find that P had a definite purpose in emphasizing the role of Aaron in addition to that of Moses.
The seat of the Davidic dynasty, which was promised to be everlasting, came to an end on account of infidelity to Yahweh. It will be the community of the faithful under the leadership of Aaronite priest, who are to perform the cult described by God at Sinai, that will replace the Davidic kingdom. The authentic line of the priestly house of Zadok finally won the long-lasting competition with that of Siloe.
P's geneology reflects his scheme based on his world-view and also traces his lineage back to Adam who was made after God's image (G. 5:1) to prove the authenticity of priestly prerogative.
