Leviticus teaches us how sin must be dealt with. Sin is essentially wrong that man does to God. To have a relationship with God, the wrong had to be atoned for. The Israelite did this wrong daily. It was the natural fruit of his sinful nature. Consequently he had to make payment for his sin periodically to God. God specified how the sinners were to pay for the wrong done Him, namely by the offerings and sacrifices specified in the law.
We too sin daily. But thankfully for us, the sacrifice has already been made. Jesus died on the cross as a willing sacrifice for the sins of the world. We receive that offering as being for our personal sins, and God washes us white as snow.