True, TOS set a mild precident for the amount of Humanoids kin our Galaxy with the "preservers", one could presume or theorize as an explanation, This is "slightly" off the main topic but i LOVED the ENT episode where Dr. phlox is examining a humanoid from a future fed starship and informs Archer and T'pol he finds this "human" has trac genetic markers from dozens of species, In some ways it is ironic because in Ds9 security officer /maquis spy Eddington accused to sisko that starfleet is no different than the Borg in how they assimilate everyone into the Federation without them realising it, well many people i have discussed this with agree completely, It's a hallmark of the irony of why the Borg are IMO the best trek villain of all time, they remind us, or foreshadow, of ourselves and what we could become if the path to Utopian perfection continues uninterrupted, this is a theme that is the main point of my Daystar series.