One interperetation I see is that the law was shown to humans to show us how we should live.
All in all, the laws are pretty good, quite functional.
Humans being humans err, and keep erring.
Quote:......... For what I want to do I do not do, but what I hate I do....
..... As it is, it is no longer I myself who do it, but it is sin living in me.....
For I know that good itself does not dwell in me, that is, in my sinful nature..........
Poor Paul, there is a wrestle on within himself. The sin within him continually tempts him.
Eventually, the cost of the "slip-ups" is a spiritual death.
It is impractical for him to atone for his every sin, and to never sin again.
There is no sin in God, so no sin can abide with God.
For any sin, a penalty is to be paid.
To "undo" a sin, a price is to be paid. Something real, something that costs.
In the OT the penalty was often the sacrifice of a dove, lamb or the like.
It is the blood of this sacrifice that pays for the sin.
Of course, it is possible for an innocent party to pay for your sin.
Imagine being fined in a court for speeding, it is quite legal for someone else to pay your fine, to supply you with a dove or lamb for sacrifice.
The fine is paid, you are free to go about your way.