@Tcmc: Jesus had to give his blood because that is the ultimate scarifice. When Adam and Eve sinned, they were cursed to die to pay for their sins. They would be eternally seperated from God. And this would absolutely be the case unless their sins are attoned for.
Before Christ came, the blood of animals were used as a temporary payment. However, even if the blood of men was used it cannot be satisfactory enough in the eyes of God. However, the blood of Christ could pay for our sins because He is God incarnate. Christ is fully man but at the same time fully God. God knew we could never pay the price of our sins and yet because He is right and just, there is no way He could go against His words regarding Adam and Eve's sin. We all have to die an eternal death and be seperated from Him. That is why propelled by love God humbled Himself and took on the form of a being He created, to suffer humiliations and rejections by the very creatures He created, to suffer abuse by the very creatures He left the glory of heaven to save. Nothing else is more precious than the blood of the Son of God and hence only His blood can wash us clean from all sins, and not vegetables or anything else.
Blood scarifice is also prevalent in so many other cultures and religions because the ancients knew it is something very special, very precious as well. Although they were wrong because the blood of mere men and animals can never attone for our sins.
"Greater love has no one than this, that he lay down his life for his friends." John 15:13
Christ loved us so deeply and so greatly that He lay down his life for not just His friends and disciples, but for the soldiers who stabbed Him, who slapped Him, who spat Him, for those pharisees who hated Him, who accused Him falsely. For all of us sinners He would even endure a horrible death on the cross. What can be greater and more precious than His love and blood?