But when the Bible teaches the sacrifice of Christ did away with the law of Moses and carnal commandments, why should we think it did away with laws given before the law of Moses?
First off, he didn't do away with the law:
"Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them.
Second: he says the "Law or the Prophets" in this verse. Which would go back before Moses to the prophets.
third. There are several passages that use "law" in general in saying that he fulfilled them. The Law, the Prophets, and Moses's law work interchangeably. They all mean the law of God in some aspect either in relation to the Jews or all men.
I'm really not getting your direction. The law before moses is the same laws that existed with moses. God gets on to people before Moses for breaking his, quote "Laws and Commandments." So they did exist before Moses. I think you splitting hairs to try to denigrate Jesus fulfilling the law doctrine..