It is a logical fallacy to claim that you must be the "all knower" to make any moral judgments. You make moral judgments all day long, and you are not the "all knower."
Your assertion that "God is the only all-knower" and that the Bible is his "manual" has no foundation in fact. That is merely an assertion that you make, and in doing so you have set yourself up as the ultimate judge who "knows" something that is in fact quite false. The Bible cannot be the infallible and inerrant Word of God because it cantains errors, contradictions, and moral abominations attributed to God. Now if you go about trying to "fix it" and "explain away" all its problems, you will be setting yourself up as judge and interpretor of the Bible, and that means that the Bible is not "guiding" you at all. You are merely using your own intellect and moral intuitions as the ultimate guide when you use them to "fix" the Bible.