Blood contains all the information you could need on a person. Science explains Gods’ works. God is science. 

The blood of bulls and rams was used but it wasn’t sufficient because animals don’t have the same characteristics as humans. Animals aren’t thinking-feeling species. They can’t gaze in wonder and amazement at His works… but a human can. 

The Purest human. The Glorified King. The one who was able to withstand all temptations because of the goal. He knew if He contaminated His blood, it would have been useless for us. 

That’s powerful love. 

Hebrews 10:7