Before Christ the blood of goats and calves were a temporary covering of sin. Jesus shed his own blood so we could be cleansed from our sins once and for all. In Hebrews it says, “But through His own blood, He entered the holy place once for all, having obtained eternal redemption” Hebrew 9:12 (NASU).
Our redemption could only come from the sacrifice of a spotless lamb. It was obtained by the blood of Jesus. Only His blood could redeem us because only Jesus lived a perfect life. He was our spotless lamb.