I think codexes do make it clear it's hardly "nobody" - there are settlements with several families living a quiet life on distant planets. Off-Earch Human Census puts the number of people living out there in space at 15 million, and an entirely unknown number of humans leading nomadic lifestyle. Humans spread out greatly during these thousands of years. There just hasn't been any large scale colonization, since humanity had all they needed on Earth. While many would explore the universe in their travels, they'd return eventually home once their travels were over. I don't understand why everyone seems to insist that there's a huge problem with this kind of situation? It sounds perfectly understandable to me. How come? While they might not be the focus of the story, there's plenty factions that don't belong in either. Floran tribes, Glitch kingdoms and knight orders, Stargazers, grounded Avians, Hylotl underwater cities, Novakid villages... All of these, and more, function completely independent from either side. Stop acting like the main story is all there is to the universe.