There is something wrong with Jasher here as regarding v4 and seems to have been missed by many.
Can you see that? It is something Paul makes extended usage of in Romans.
I will wait and see for others to reflect on this, maybe someone else can draw that out from this murky water.
Romans 1 says all men once knew -
Paul referring to the Torah as given by Moses for the Jews, is not to be confused with God giving men His Word and commands from the beginning of creation.
Noah preached the Word of God for 120 years before the flood was sent. He did not preach Moses' Law which was given by Covenant to the namesake people of the New Man name ["Israel"], 430 years after the promise to Abraham.
Noah, as the priest of God and king of earth as head of all the tribes who would descend from him through his sons, was given the "law" for all nations, by God the Word, when Noah came off the ark.
You will find that in Genesis 9.
BLB - Gen 9: Book of Beginnings - Genesis 9 (Blue Letter Bible: KJV - King James Version)
Noah also knew what animals were clean for sacrifices and eating and what animals were unclean for sacrifices, so seven pair of the male/female clean animals were taken on the ark, whilst only one pair of the male/female unclean pair were taken on the Ark.
Noah and Shem also instructed Abram/Abraham in righteousness for 30 years, whilst Abram dwelt with them, from age ten, while hiding out from Nimrod [Amraphael of Genesis 14], who wanted to kill him -that is in the history book of the upright.
Blood sacrifices offered on the altars made by men and offered up with prayers to God for forgiveness of sins were made from the time of Adam's fall, when the head of the Adam race -who carried the seed of all who would ever come forth in the Adam-kind spirit- was
cast out/divorced [same meaning in Hebrew for the English word] from the presence of the Creator, in Eden above.
The entire race of Adam =all the sons from the firstborn in Adam- right down to Noah and to his sons after the flood knew what God accepted as sacrificial offerings. Even Paul says in Romans 1 that all [the entire human being race] once knew God, and changed His glory into the created things, and worshiped the creation, so God gave them up. Psalm 9 also agrees that the nation that forgets God will be turned into Sheol.
Many nations once knew God. YHWH says Egypt did, and will also once again return to Him.
But no Gentile nation was covenanted with, by YHWH, to bear the name of the New Man [who was to come as God in Flesh] and to keep the signs of His Person and work, by the rehearsals of the signs in the feasts given only to those over whom His New Man name, as God come in flesh, was invoked.
That name was invoked as a sign of the adoption that was to come, by the Acceptable Sacrifice/Atonement, which Adam was promised would come in Genesis 3, and which Abraham saw -with his own eyes opened- when he obeyed the command to offer his "only begotten" [=Monogenes, as the Greek translation says of Isaac, though Ishmael was Abram's firstborn son, just as the NT calls Jesus the "Monogenes/only begotten son of God, even though Adam was the firstborn son of God -Luke 3].
Job was not of Israel, but Job was a righteous man and knew God and kept His Law. He did not keep the Law which came by Moses and which only came to the namesake people of the New Man name, who covenanted to keep it forever, at Sinai, as God's signs of His Person and Work to redeem the race by the Atonement and adoption as sons, named Israel in their flesh of regeneration, and not Adam any more. Isaiah 49; Genesis 5:2 show us the old man name and the New Man name.
Gentiles are under the Law Noah gave of moral righteousness and were never required to come under Moses to be in right standing with God -as the Scriptures clearly teach, for the promise to Adam in Genesis 3 looked forward to the Atonement for all the seed to come out of his loins, and all once expected that Messiah to come -but the nations forgot God.
Our nation has forgotten God, and will be turned into Sheol and pass away like all who have forgot Him before us, unless there is a mighty turning to God like Ninevah did in the time of Jonah.
Jonah did not preach for the Gentile Ninevite population to come under Moses, but to repent of their wicked sins, as children descended from Adam through Noah who knew better, but did evil.
So yes, there has always been "Law", but by Moses only, came the Torah; and to the namesake people, only, came Torah as a covenant to keep the signs of the Messiah's Person and work, which was to come. Even though they did not understand, they covenanted to keep it, and are still under it , but it never got a soul into Eden above, at death, but it showed how all would be able to go back, but in new garments of new creation, covered by the Blood Atonement of the Kinsman; and be adopted as sons in His New Man name and be priests of God and reign with him from His holy Hill above- right where Adam was cast down from, at the fall.
Job 22:22 Receive, I pray thee, the law from his mouth, and lay up his words in thine heart.