The Bible contains all sorts of commands that God wants us to know about, which are not directed toward us personally. If we are not concerned about building parapets around the roof of our houses (Deut 22:8), we should nonetheless delight in a God who cared that houseguests not fall off a roof with which they were unfamiliar, and therefore he taught his people to build their houses with that sort of love for neighbor in mind.
This fits into our understanding of the Law as part of Israel’s story, since we cannot know the significance of our story, the story of the new covenant, without knowing well how the Law functioned in Israel’s story, the story of the former covenant.
~ HOW TO READ THE BIBLE FOR ALL ITS WORTH
The Old Testament is NOT a throwaway.
God reveals himself through many avenues. One is through the special laws he selected to separate a chosen people for himself, recorded in the Old Testament and sometimes explicitly expounded upon in the New Testament. Many of them make no sense to me, but over time and with guidance, I’m chipping away to understand their relevance to who God is.
The clearer I see the old covenant he gave them, the more sense the new covenant makes for me. And the more I understand the God in their story, the better I understand Him in my own.