In my opinion there is total knowledge broken up into what you know and what you don't know. To fill the gap of what you don't know, religion was created. Initially a force (thunder perhaps ) was recognised and so they created a god of thunder (Thor).The "forces" were personified into gods. This is where corruption creeps in. If you want to encourage a god to do somethng you've got to give them a gift, eg a lamb. With lots of gods this meant losing lots of lambs and there is a nomadic tribe who had a penchant for economics and suggested that there was only one god who could multi-task and so they could cut back on the number of sacrifices.
However never let this get in the way of making a profit and so it was that sacrifices must be of unblemished sheep.Well just by coincidence around the back of the temple there is Uncle C and he has a flock of unblemished sheep. Wow. What a coincidence!
I would encourage you to look up " The god of the gaps" this is a conclusion that you have obviously come to yourself(great job). This simply means that when theist do not know something they just assume that god must have done it. God fills in the gaps of knowledge and therefore there is no reason to invesigate futher.
As far as the unblemished lambs etc. the reason for this is they were the best stock and thus a greater sacrific. The problem wih this is when you always and continuously kill your best stock after a time all you are left with is substandard stock. This is not benifitual to anyone, in fact it makes future sacrifices substandard. It would be better to sacrifice the worst of the stock so that in the future the pool to choose from is of a much higher quality. Evidently god has no clue about genetics.
Lots of disparate ideas thrown together but at least you’re thinking. Welcome to the Machine!