You are saying that any system of morality is entirely subjective.
It appears that way to me. Although it also appears that there are some that seem to be inherent in most civilised persons, throughout history. I think, what it really boils down to, is that the subject of morality, for want of better terminology, cannot really be put into a black or white category. That is why I say that we as humans will strive forever, and as hard as we can, to try and find some moral absolutes...but, in reality, there will always be an exception to the rule. I chalk it up as one of God's mysteries, that we probably will never understand or totally agree on.
Have you come to a conclusion about whether taking a human life is right or wrong?