All sin brings death. Sin is sin. We do it on purpose. We do it accidentally. And it must all be punished. So God gave His people a system of substitutionary justice, whereby an innocent creature would take your place and take your punishment. When you sinned, you would not pay with your own death, or even by losing a limb. It would not cost you an arm and a leg. A substitute, which you provided, would take the fall.
By our modern sensibilities, I can imagine people being outraged at the deaths of so many lambs and goats and cows. “Why does God demand this? If He is going to forgive us, why not just do it without the bloodshed?” Because otherwise He would require your life instead. Justice is what the judge determines, not the mob. And our judge is also our creator, our master. It is to Him that we give account. Then, when He determined the time was right, He sent His son to be the final sacrifice. We should be happy He did.