If we understand the Garden of Eden to be a sacred space for God to dwell, we can begin to see Adam as a king and priest over all humanity. This language, of course, is not related to Adam in the Bible, but he does seem to fit these roles. If he has such intimate access to the presence, then he is able to speak and work on God’s behalf like a priest. Likewise, since he’s charged with subduing and ruling the earth, he also acts as a king of sorts.
This king/priest role seems to be a special position God hopes all of His leaders to partake in and the idea really is quite beautiful. For if a king is also a priest, then he would be able to lead God’s people while maintaining a special connection with God and serving in His presence. The time spent in the presence would then be the key factor influencing all that the king does. But this kind of role in God’s kingdom is eventually done away with in Moses’ time as a concession to Moses, for he was dead set against being a public speaker. Therefore, God allowed his brother Aaron to take on the priest role and left Moses in the king-like role (Ex 4:10-16).
And so due to Moses’ desire and not God’s, the king/priest role is spilt and will remain split for the rest of the Old Testament. For now on the ruler of Israel will not play the part God meant for him to play—or at least he won’t play it with the fluidity of which he was supposed to. Aaron and the Levite clan will now serve as the priests of God and Aaron will now play a strange mediator role between God and Moses and Israel.