I'm not disagreeing with what you say, but I don't see how it pertains to what I think we're talking about.Not the letter of the law, but what the law revealed.
The law revealed that, because of a spotless one, you would receive a pardon (that you didn't earn) instead of the guilty verdict you deserved (that you did earn).
The works of the law (ie. the ritualistic deeds that were done) demonstrated the grace of God.
For while those works of the law were performed by various entities (from the sacrificial offering itself to the high priest) ALL were a demonstration of what God Himself would do alone.
Christ was the offering and the high priest and everything in between.
Noah was not the only one saved on the ark from the flood.
And the remnant of 2 of those son's descendants would persecute the remnant of the other son's descendants.
Grace is like oil and oil and water do not mix.
And if by grace, then is it no more of works: otherwise grace is no more grace. But if it be of works, then it is no more grace: otherwise work is no more work.