The Borg was one of the most fearsome villains in the Star Trek universe and rightly so. With the ability to strip a person of their ability to think and act as an individual, they were often seen as a force to be avoided rather than confronted. In Star Trek: First Contact, the Borg Queen was introduced, and she appeared to be a representative of the entire Collective rather than an individual. But in her reappearances in Star Trek: Voyager’s Dark Frontier and Unimatrix Zero, she gave orders to the Collective, and it was clear that she was in charge which essentially established her as a separate entity. Ronald D. Moore, Brannon Braga’s writing partner, told AOL in 1997, that they had intended the Queen to be a literal person which meant that each Borg Queen had to be assimilated first. But the Borg Queen in First Contact wasn’t meant to be the first queen.
And the producers of Star Trek: Enterprise intended to introduce the first Borg Queen and where she came from in the fifth season of the series had it not been canceled. They wanted Alice Krige to play a Starfleet Medical Technician who made contact with the Borg from the season two episode, Regeneration. That contact would have resulted in the birth of the Borg Queen. So the very first leader of the Borg would have been a member of Starfleet?
What’s interesting is that there is no information as to exactly how an individual is chosen to be the Queen after that first assimilation occurred. In the Voyager novel, The Farther Shore, it was established that a Queen could be replaced in mere seconds by using the Royal Protocol. And supposedly, Seven of Nine was most likely to become the next Queen. There are, of course, other theories as to how the Queen was chosen like some say the Queens were from a specific race that exhibited superior higher-order brain processing-speed, but that hasn’t been established as canon.
Perhaps Star Trek: Enterprise’s plot would have explained the entire process. Maybe not. One thing is clear, though, this is an open plot that could still be explored.