The flaw (or point) in ur argument is that everything is questionable or "everything is relative". Scenario 1 is based essential food items available at the different parts of the earth, like grasslands, extreme cold & hot climates, etc... Here the religious rules are modified to suit the existence of life or the accepted fact becomes the religious rule.
Scenario 2 is egoistic clashes, when people in the scenario 1 from different places come face to face with each other. It is here, that the flaws in our thinking is reflected by the bloated ego of the human mind, which simply doesn't understand and the result the spillage of blood.
Your Truth is questionable and as questionable as you question others. Besides, the other most major flaw in our thinking is "There is ONLY ONE GOD" concept. What if mankind didn't exist, do you think GOD would exist?
GOD is the dreams, whims and fancies of men and not Vice-versa [The Great Mahapurana, 9th Century]
