We cannot be ignorant of this concept. The work that Jesus did on the cross was first. It was not chronologically first but eternally first (according to Hebrews 9). The sacrifices delineated in Exodus and Leviticus were precursors to what Jesus did in eternity once and for all time on the cross. Remember, the blood represented signatures on a contract between God and man in the Old Testament. But because we kept reneging on the contract, there had to be a system in place to keep the contract in effect. God knew from the signing ceremony that we could not live up to the terms of the agreement, so he instituted the sacrificial system. Every time the contract was breached, there was in essence an opportunity for individuals, families, and/or the entire community to participate in another signing ceremony. So he would forgive the breach and make another agreement. That’s why we had to sacrifice over and over again. That’s why we had the system-to create a new agreement/contract every time we sinned. But Jesus’s sacrifice was the true course (original plan) to fulfill the requirements of God’s price for our souls, thus fulfilling the requirements of the law for man forever.