Abraham was taught this order by Shem, and he taught that same way to all his children.
Midian was one of Abraham's sons by Keturah. Midian then taught his own children, and that pattern continued down through his line. Some 400 years later Jethro is called a priest of Midian. Through this line the children of Abraham continued to worship God as Abraham had taught them.
Isaac, also a son of Abraham, worshiped as Abraham, as did Jacob son of Isaac. They built altars, the same as Abraham.
Jacob wrestled with God and was blessed by Him and given a new name, Israel. Israel declared, he saw God face to face.
God saved Israel's family from a famine by the hand of his son Joseph and gave them the land of Goshen in Egypt.
After Israel and Joseph died a new Pharaoh came into power who did not know Joseph and he soon made slaves of the Israelites, and they continued that way for some 400 years.
Remember what happened after Ham's rebellion. His descendants moved south into the flatlands and built great empires, Egypt and Mesopotamia.
Both centralized their power in great cities. Their kings surrounded themselves with lesser kings and princes, consolidating authority through military might, controlling commerce and trade, and establishing state religion.
They set up priests and prophets who claimed to speak to God on behalf of the people and who worshiped on their behalf. In this way the people were taught to depend on these men instead of coming to God themselves.
They built large temples with sacred places only the priests could enter. They separated the people from God. This was the beginning of institutionalized religion and it stood in direct opposition to the Order of Adam.
This is the world the children of Israel lived in for some 400 years.
Moses, an Israelite who was raised in Pharaoh's house for 40 years, fled Egypt as a fugitive. He came to Jethro's family and was welcomed in.
Over the next 40 years he worshiped with Jethro as part of his family, for he married one of Jethro's daughters.
In Jethro's family Moses lived the older pattern of worship that had come down from Abraham.
At the end of forty years, after Moses had been shaped by that older order and had become very meek, God spoke to him and led him to bring the children of Israel out of Egypt.
Not long after being delivered from Egypt, God directed Moses to teach the Israelites how to worship as their fathers Abraham, Isaac, and Jacob, every father a priest over his own family, a kingdom of priests and a holy nation, the same order Adam was given in the Garden.
However while Moses was on the mountain communing with God, they pleaded with Aaron to make a golden calf so they may worship as the Egyptians did.
After 400 years in Egypt, they wanted priests to stand between them and God. They wanted a temple they could see. They wanted what Egypt had shown them, just with the name of their God on it.
Through this and other experiences the children of Israel made it clear they wanted to follow the pattern of the empires, not the pattern of Adam. So God gave them what they asked for.
He gave them priests to worship for them, the Levites, and a law suited to a people who had refused the higher way. He also tied the older holy days and sacred remembrances to the Exodus they had just lived through. Over time those things became more complicated and more institutionalized.
However this system was still designed to lead them to the Messiah who was to come. Also God preserved the heart of the older order: to love God with all your heart and to love your neighbor as yourself.
For the next 1,500 years God would raise prophets from among them, men who were able to live the Order of Adam, offer an acceptable sacrifice, and come into the presence of God. Again and again the children of Israel resisted and rejected them.
Then the Messiah came.