What was the purpose of clean and unclean things in the Old Testament?

When God gave the Law to the Israelites, He did so with the intention of showing them how to live in every aspect of life.  Many of us today are confused by the regulations that were put in place by God through what the Israelites could eat (Leviticus 11), wear (Deuteronomy 22:11), what to do with their sick (Leviticus 13), etc.  As far as food is concerned, the animals God told them were unclean are actually unhealthy to eat.  The reason for the not wearing clothing made of different materials is because they are hotter in a desert climate than just wearing a garment made of the same material.  And the sick were removed from the rest of the camp to ensure the disease would not spread.  Everything had a purpose to what God told them to do and while these are not everything, they should help in understanding God’s reasoning.