In a very helpful conversation with CJ Bowen and Joshua Appel, they pointed out how Jethro acts as a father and a judge in Exodus 18, and this is a type of Yahweh.
Yahweh is the Father and Deliverer-Judge of Israel; He has brought Israel out of slavery and bondage to a false father-judge (Pharaoh). That false father set taskmasters over them and worked them with rigor, but their True Father frees them and exalts them, giving them responsibility and authority. This continues through the counsel of Jethro who comes as a father (literally, a father-in-law), and he sees the state of Moses judging the people and judges this “not good.”
Jethro urges Moses to give authority to the people, setting up rulers who judge the people. And this involves Moses replicating himself. Though it is only Moses who is initially judging and teaching (18:16), after Moses has selected the rulers/judges, they are trained/taught (18:20) so that they can teach and judge the people (18:26).
This intent is even more explicit in the parallel passage that occurs some time later in Israel’s history in Numbers 11. There it is explicitly the Spirit that is upon Moses that God takes and puts on the seventy men of the elders of Israel (Num. 11:16-17). As a result of the Spirit coming upon the seventy men of the elders, they prophesy, and though some where concerned about the charismatic outbreak, Moses prays that all of the Lord’s people would be prophets and that the Lord would put His Spirit upon them (Num. 11:29).
Some commentators puzzle over why God speaks through Jethro when up to this point He has usually just spoken directly to Moses. But the fact that God is speaking through Jethro exemplifies the whole point Jethro is making. Yahweh has blessed and equipped Moses, but the point is to share that blessing with others. God will bring the people to their place in peace as they are led and shepherded and taught by many faithful rulers. The goal is to make all of God’s people “priests and kings,” judging and teaching in righteousness.