I down voted this, because it feels like baiting, except that dang you went into a long rant about all the assumptions about the innateness of hierarchy. Fuck it - I take the troll bait.
No. You assumptions are wrong, at least if taken as universal - lots of animals live without hierarchy, as do lots of human animals, unless you discount pre-civilized life, and the realities of lots of groups that eke out livings on the fringes of our world. A survey of anthropology will provide plenty of examples of people who lived without hierarchy. If you happen to want to have civilization with your anarchy, you might be disappointed by the record so far, at least so far as those working in favor of civilization and order go (you know those two go together, right?). Your disappointment with this is not my problem. If it is too much, read something from the Institute for Anarchist Studies, they are more optimistic than I am.
You say you want to equate hierarchy with human nature, but what is human nature? You seem to have one idea, but I bet that you could find a dozen other people with a dozen other ideas about human nature. I personally don't give any weight to the term, not because I don't think there are shared traits between groups within our (presumably shared) species, but because I think that most often when people talk about "human nature" they most often mean shared traits of civilized humans, as opposed to expanding it to include all humans.
I would disagree also with your idea that we experience hierarchy from the minute we are born. Hierarchy is not exactly the same as unequal power, even if crimethinc and bookchin could lead you to believe such. A mother nursing and tending to a baby is not hierarchy, that is a mother being a mother. There will be people who dispute this, but I don't think parents necessarily exact hierarchical power over their children just by tending to their needs.
Power comes in to play when they try to influence their children in particular directions. Certainly, anarchists can exert their own power in trying to make a child an anarchist, but they don't have to. What stops us as anarchists from teaching children about power and teaching them that they should end up trying to destroy or move beyond our ways of understanding or engaging with things? Not much unless you think anarchy is a particular thing that we are working towards, but you wouldn't have posted to this site if that was your assumption, right?