Having read through Leviticus, you'll notice the phrase "clean/unclean" alot. You'll also notice that lots of words are spent describing bodily cleanliness (discharges, rashes, skin diseases), mold issues, animal issues, sexual issues, sacrificial issues. God wants his people to live as a "clean" nation.
This has a ceremonial/religious element to it, as well as a sanitary/social element. Since they are a new nation, God is carving out for them new standards for how they will conduct themselves - thus everything has to be spelled out in detail (lucky you who gets to read it!). God is contrasting his new commands for this new nation against the ancient practices of the Egyptians that they left behind, and the established ways of the Canaanites they are about to encounter in the Promised Land.
So God uses the concept of clean and unclean, an idea that touches on the inside of their body and the outside. Think about how practical it is to have regulations for contagious skin diseases amongst a nomadic people living in cramped quarters with no efficient sewer systems or bathing facilities. If God doesn't want an epidemic to break out as they travel through the wilderness (and for when they set up their new nation), he needs hygiene rules. Same issue for the mold: mold can be very annoying and debilitating if left unchecked. And in regard to sexual practices, God wants to prevent the abuse of women (which was common in the ancient days), he wants to prevent sexually-spread diseases, and he wants to establish ground rules for how husbands and wives ought to relate sexually to each other. This is all in contrast to the surrounding nations and their habits.
God wants us to be healthy, happy and holy according to his perspective. All of the details listed in Leviticus don't apply to us - we're not ancient Israelites. But the theme applies to us: how we approach God is important. How we conduct ourselves in the name and sight of God is important. If we claim to be his "children", if we have become "citizens" of his kingdom, then we ought to conduct ourselves according to his expectations. God gives us regulations on how to live in His Creation so that we will be healthy, happy and holy. How that gets applied today takes the same disciplined, rigorous work that it did over three-thousand years ago.