I've finished rereading Exodus plus Leviticus, and now I'm in Numbers. So far, the rules that God has set down (or so the Levites would have everyone believe) deal mainly with the details of sacrifices and religious observances in the sanctuary and to unclean and clean states of being. Many of them seem to be temporary, i.e. limited to the time when God's sanctuary was a tent in the wilderness. Others are "permanent statutes". All, however, are directed entirely to the people of Israel and to nobody else, so I'm not paying too much attention to them at this point.
There is an interesting episode in Numbers. Some Israelites go into Canaan as spies to get the lay of the land, and all but Caleb and Joshua counsel caution and warn that the Canaanites are formidable adversaries. Later, some Israelites attempt to enter Canaan and are, in fact, slaughtered by the Canaanites. This is said by Moses to be their punishment for not believing Joshua and Caleb that they could easily take Canaan. Really?
In these books, God talks to Moses directly and appears to the people as a cloud of smoke by day and a pillar of fire by night. He likes the aroma of burning animal flesh, and He can't stand whiners. He aims to make Israel a nation of priests. Within the nation of priests, you have the Levites as priests and the House of Aaron as superpriests. I'm going to go out on a limb ad speculate that the Levites had a hand in writing these books.