Blood has been used or kept sacred by the ancients of various diverse cultures. It is VERY powerful. The Hebrews / Jews knew it was so powerful that they kept it only for God. That's why they don't eat blood. Various african tribes use blood for strength. Some slaughter an animal & give the fresh drawn blood to the ill to make them strong again. Others use it in rituals, etc. Your other points could be valid too but I know the ancients knew there was life power in blood