But we do know where we come from! We have an awfully nice selection of now extinct inhabitants of the genus homo, and we can ballpark when the last common ancestor of humans and chimpanzees lived.
I don't believe "we can ballpark" is a synonym for "know".
You're demanding absolute and precise knowledge is really arrogant. There are no guarantees that there ever will be answers to the degree that you apparently require, although I am not sure who you think you are to be asking of such precision. No one has that right. We have to earn it, as a species, by putting together the pieces, if they even still exist. it is akin to piecing together a crime scene. I know that is disquieting, but the certainty that is available through religious faith does not reflect reality simply because that belief is personally and/or emotionally satisfying. In fact, the satisifaction your mind gets from having faith has no bearing on whether your beliefs reflect reality. You are basically bending the universe and all of its laws to fit your mind, so that you feel good about it... it is so proposterous it makes me want to puke. It is the height of egocentricity, the height of hubris. I do not know how you are missing this. Believing in science is a humbling prospect, one where all of the knowledge is not known, where people actually have to work and study and put in sweat and toil simply to acquire the data that then needs to be put into a working model and then theory, all when there is no guarantee that will ever find what you are looking for... creationists simply take a fairy tale, call it true, and tell everyone else they are wrong. It is completely hilarious, insulting, disrespectful, disingenuous, and enraging all at the same time. the anti-intellectualism that faith has come to breed is simply no longer acceptable to me. I only wish I could more poetically express my rage towards these faith-based monstrosities creationists call arguments.