I never said "nothing changed" I said in Heb 7 it talks about the "law" that changed and that was the priesthood, because the law stated the priest needed to come from the tribe of Levi, but Jesus came from the tribe of Judea. Do you see what that law- the priesthood needed to be changed? Which is the context.
It talks about the law of fleshy commandments- which is Col 2:14 Esp 3:15 which are the commandments contained in ordinances. What laws are these that were under the Levitical priesthood.... the context tells us
Hebrews 7: 27
who does not need daily, as those high priests, to offer up sacrifices, first for His own sins and then for the people’s, for this He did once for all when He offered up Himself.
So its referring to the animal sacrifices under the Levitical priesthood, that their blood made nothing perfect and could not take away sins. It was always just a placeholder for Christ who's blood can cleanse us of all sin and unrighteousness.
Hebrews 10:4 4
It is impossible for the blood of bulls and goats to take away sins.
5 Therefore, when Christ came into the world, he said:
“Sacrifice and offering you did not desire,
but a body you prepared for me;
6
with burnt offerings and sin offerings
you were not pleased.
7 Then I said, ‘Here I am—it is written about me in the scroll—
I have come to do your will, my God.’”[
a]
8
First he said, “Sacrifices and offerings, burnt offerings and sin offerings you did not desire, nor were you pleased with them”—though they were offered in accordance with the law. 9 Then he said, “Here I am, I have come to do your will.” He sets aside the first to establish the second. 10
And by that will, we have been made holy through the sacrifice of the body of Jesus Christ once for all.
With the death of Christ He became our High Priest so no more animal sacrifices for sin, we can now go directly to Jesus when we sin, but when He cleanses He says go and sin no more.
Sin is still the same in the OT as it is in the NT.
Breaking any of the Ten Commandments
1 John 3:4 4 Everyone who sins breaks the law; in fact,
sin is lawlessness.
James 2:10 For whoever shall keep the whole law, and yet stumble in one
point, he is guilty of all. 11 For He who said, “Do not commit adultery,” also said, “Do not murder.”
Now if you do not commit adultery, but you do murder, you have become a transgressor of the law. 12 So speak and so do as those who will be judged by the law of liberty.
Romans 7:7 7 What shall we say then?
Is the law sin? Certainly not! On the contrary,
I would not have known sin except through the law. For I would not have known covetousness unless the law had said, “You shall not covet.”
Jesus came to save us from our sins, not in sin, and why He teaching not to break or teach others to break the least of these commandments because in doing so one would be in fear of sin and Judgement. Mat 5:19-30