Five Books, One Story
Almost no commands. Paul notes the law came 430 years after the promise to Abraham (Galatians 3:17). Grace came first.
Israel is rescued before a single command is given. The covenant is read, the people agree, and Moses seals it with blood (Exodus 24:7 to 8).
Priesthood, sacrifice and purity, all built around God dwelling among His people.
Moses restates the covenant to the wilderness generation and has the book placed beside the ark (Deuteronomy 31:26).
Under Josiah the book of the law turns up during temple repairs, and hearing it read sparks a reform.
Rome destroys the temple. Priesthood and sacrifice stop inside the generation Jesus named.
So the law of Moses is not a rulebook with a story stapled to the front. It is a story with a covenant in the middle of it. Genesis belongs to the Torah because the Torah is the whole account of how God made a family into a nation and bound Himself to it.
Strong's traces it to yarah, to teach. The picture is somebody pointing out which road to take.
Brown-Driver-Briggs gives direction, instruction, law. It can mean one ruling, a whole code, or a mother's teaching in Proverbs 1:8 (see the lexicon entry).
By Jesus' day it names the five books. Luke 24:44 speaks of the Law of Moses, the Prophets and the Psalms.
The Greek translators rendered torah as nomos, law. Not wrong, but narrower. Instruction includes law, and also story, song, warning and promise.