Part of what makes the Star Trek TNG episode "I, Borg" so confusing for me is that the Borg in their first episode, "Q Who", seemed like their own species. Half robot, half biological entity race. Then they talk about freeing Hugh. Wasn't Hugh always a Borg though? The "I am not Borg" thing is confusing. It's as if they weren't their own race
What we learn about the Borg is they either assimilate individuals of other races, or create their own young in incubation chambers.
As such, the Borg are a variety of races.
Why do they seem like one race?
- Star Trek very much endorses the idea of "Planet of Hats": Each race gets a dominant characteristic, and they bang that drum really hard: Warrior Klingons, Logical Vulcans, greedy Ferengi, conniving Romulans etc. If a Norsican boards the ship, this won't be a romance story.
- So one is conditioned to thinking "pattern behavior ~= race". With the Borg, they all act exactly the same (hive mind and all). So they seem like a race in that sense.
- They are so covered up with cyber gear all over their heads that you can't really see what race they are. And they didn't really bother showing us any distinctions until we got to know the Borg a lot better in Voyager.