In "Q-Who?" (the first Borg episode), it was heavily implied that the Borg were just one humanoid race, which started out as fully flesh-and-blood, and then the implants were added over time (hence the scene with the baby). It was even implied that Hugh and the other rogue Borg were also the original Borg "race."
It wasn't until FC that it was decided that the Borg were in fact assimilated from multiple humanoid alien races (which probably grew from the idea of Locutus). And it was also where the idea of a Borg Queen came from. And yes, I would have assumed that the Queens were the original Borg race in this new retcon. But they weren't.
So if the Borg are nothing more than other races being assimilated, how did the Borg collective start? My issue is that the original intent for the Borg (at least what we saw in "Q-Who?") gives them the right to do whatever they want as far as choosing to be cybernetic, because all they are affecting are themselves. The problem then becomes that they were made to look like they were intentionally destroying other races simply because they were not like themselves. The later idea of actually assimilating other races into the collective instead of just destroying them gives more of a method to their madness, but then creates the paradox that there was never an actual Borg race to begin with (unless we are told otherwise in the future. Yes, I know about the novels' take on this, but quite frankly, while I like reading Trek novels, I found their take to be needlessly convoluted.)