Chrissy Jaeger - Sacrifice the one for the whole

This is my first blog, I really have no idea what I am doing because I have never "blogged" before, so here goes nothing:
I was reading in Original Visions, and on page 59 Carmody has been talking about sickness and how sickness is based on the assumption that wrongdoing has occured. "The sickness of the individual threatens the tribe..." There is this underlying idea that the individual holds responsibility for the ill fortune of the tribe. This also works vise-versa as Carmody mentions. But I want to focus mainly on this idea of the individual. The next paragraph begins to bring up solutions to this problem, one of them being sacrifice. For this tribe usually an animal sacrifice of sorts is the solution to get the attention of the gods. I am reminded of a story in the bible of the Israelites traveling in the desert awaiting their promised land. God gives the Israelites strict rules and one guy out of the all the tribes of Israel breaks these rules. This causes the all Israelite tribes to suffer. Once this man confesses to his sin, he is taken and stoned. This sacrifice is made in order that the Israelites may again be in harmony with God. So, what is it about sacrifice? Why not just change the sin- or shun the one individual who was causing wrongdoing that jeopardized the tribe? Why a sacrifice? My real question comes from this -Where did people get the idea that sacrifice pleased gods or God?
It seems to me that the only way to discover what would please the gods or God, would be a "live and learn" kind of experience, or that God told the people what he desired. Hopefully it would be more along the lines of God telling the people what he desired, otherwise people are sacrificing others with no assurance that there will be a desirable result. So, then we are brought back to the question why sacrifice? Why is sacrifice in some form often the answer, for many oral traditions, to fix the problem? Is it that blood is the way to cover, or wash clean what has become damaged or dirtied?