I guess that's just people being people. Even interpreting first-hand experience isn't perfect, much telling others of it, and what gets created out of that. I mean, we have the N-th copy of an N-th hand oral account. That's just, you know..
But why don't we get born enlightened? I don't know. That's where (a lot of) religions come in, with the "X went wrong, do Y to fix it" stuff
And actually, do these things really differ in so many ways? Be honest, don't forget about the poor, the orphans, the widows, the elderly, the sick, those in prison.. be grateful and willing to help those in need, don't kill (okay, there is the "unless god mandates you to" stain on that, but it's a start?), and so on... compared to that, is wether someone prays 5 times a day or partakes in communion each weekend really *that* important? and no, I don't mean to just list islam and christianity, I just don't have time to research the commonalities between religions before posting ^^
In my mind, that's at best something to get people started (which may have merit), some kind of focus; but it also can seriously get in the way of the basic, the simple stuff, the things you could explain to any child. Love really doesn't have that many faces, it's rather steadfast, it's just us humans who are so flukey. And I think the ambiguity only really matters a lot where we confuse symbols and things, take real pride in considering ourselves as belonging to groups, as if that confers any features on us, following the rituals to the t, etc... then there's a lot of differences, and most religions in full are very incompatible with each other.
But in other ways, a lot of them have big overlap, and the image of a mountain that looks different from various angles (but leads to the same top) seems plausible as well. Personally, I think religions (in plural) work best when you take all of them with a grain of salt and simply, you know, dig around. But taken literally, and the sects who actually do think they have *the* truth? :no:, just :no:.