We are not speaking of "a way to deal with men". We are speaking of God's plan for our salvation, of God's principles. We have established that blood is required for salvation, that this does not change with time. The blood that God designates for salvation was Christ's blood, scripture states animal blood is insufficient. For 4,000 years animal blood was substituted until Christ came in our time.
The rest in the Lord is true and it is not, as you say, based on our time. It is a truth of the Lord. We cannot become righteous and saved by something we do, we become saved through blood, and that was always true.
What is effected by time is the culture of man, with people using the law incorrectly. People didn't understand what God meant when God gave law and Paul tried to straighten them out. The Pharisees got legalistic obedience mixed up with the meaning of the law. You have it mixed up with saying the law has something bad about it don't listen. You even bring up how useless it is for salvation, to argue about don't listen to it.
We need to sort the scripture out, it is all true and doesn't and didn't change. Work, salvation, walking with the Lord, working for the Lord, the Lords majesty and holiness, our inability to live without God, it all applies, all is true, we need to sort each out and put in its proper place. It is not proper to put down and ignore the law.