Man I really, really wish Voyager had done a Borg origin story.
I imagine the Borg started as sort of Communism taken to an extreme. The original Borg probably formed a Collective for reasons similar to the formation of the Federation. To acquire knowledge, to set aside our differences. Then, like Futurama's Santa, it became something nobody intended it to be, and it calculated the best course of action was to absorb everything else in the universe.
I don't think the Queen ruined the Borg, at least not in First Contact. I think the ruination of the Borg is...well, Dark Frontier. It's the first episode that really weakened the Borg just to make it possible for them to stay part of the show.