I think we can have Humans spread out throughout the stars, however they are divided. Each Human Colony is independent of others, so their not really a unified force or political power. Besides Earth, most Human colonies are just one city and a few towns, and the colonists don't feel any real loyalty to Earth, so they're not a "Faction", so much as they just exist.
Earth is a sizable planet, but because it's colonies are not tightly tied together, it's not a major player.

As for H2.0 and Pre-cataclysm Nakeesh. Okay, so they wern't the Inspiration, but they may have been some of the evidence early H2.0 used to gain support.

We should determine how long various races have been in contact with one another.