This type of reasoning is common. the problem is simply that many do not know how to rightly divide the word of God.
There were 3 kinds of Laws in the Old Testament
1) Ceremonial
2) Civil
3) Moral
the ceremonail Laws were done away at the cross
the civil Laws were for Israel ONLY
BUT the Moral laws are for all eternity
My brotha you are a little off, but but on the right track.
There's only 2 kinds of laws in the OT. Ceremonial and Moral.
I.E what God spoke directly is Moral law and the stuff that they decided they should do themselves (i.e. stoning a woman and such for certain actions) were ceremonial.
Some people think that every "law" in the bible is right, and well they aren't. Ceremonial law that is. Moral law as you stated is for all eternity.