I think there is plenty of room for all sorts of options involving those pesky humans.

I am considering changing my current Space Humans to the Space Humans described in the D&D modules a bit... they are slightly different than their anscetors in that their skin has a slight green tint as noted in the modules. Toying with the idea.

So I have Space Humans coming from a planet called Terra. Now does Terra have to be Earth, no it does not. Terra has a similar history but divergent history to RL Earth that leads to it's destruction or near destruction (basically it is an Alternate Reality Earth). But my Terra is ancient history, myth & legend at this point... the original colonists to Frontier Space came 1000's of years ago. This colony culture made first contact with other races already present with colonies in the area... now this does not jive with Zebs but Zebs colonization dates just don't work for me & conflicts a bit with AD but not much. Terra is not returned to because the colonists that became the ancestors of the Frontier Space Humans taught their descendants it was destroyed by war with themselves. Humans in my timeline destroyed their own Home World, and many of it's system colonies.  The race only survived because people had already colonized other worlds in other systems, or where on their way to colonize worlds in other far away systems on huge generational ships. Most colonies became isolated, many failed without regular ship traffic, technology stagnated and collapsed on colonies, basically the humans in the Frontier managed to claw their way back to the tech level of their ancestors but it took 1000s of years (around perhaps 10000). The humans in the Frontier are not the only Humans in space, there are other cultures out there in my thinking at different tech levels. So Humans seeded themselves and Terran life across the Galaxy.

I feel the Humans were plotting to conquer the other races but luckily the Sathar attacked and gave them a reason to work with the other three races which for most humans has resulted in a culture change of actually wanting long term good relations with the other 3 races. However there are exceptions: individuals still who want to conquer the other races or send them packing. 

So that is how I think of the Space Humans. Also the Clarion colonists committed genocide on the dralasites who actually had a colony on Clarion... again not cannon but explains the two names for me.

Now I want the various cultures on the UPF planets to be unique. So the two oldest Human Colonies that are responsible for the spread of Humanity across the Frontier need to be very different, this also helps explains different results with colonists and the other races getting along or not in the pre-history. So two ships escaped the destruction and ended up in the Frontier Lux & Argos.

In my thinking the early Colonists from the White Light System are more xenophobic, come from a rigid class based society, and they were isolationists until a jump capable ship showed up. This burst the bubble of we are alone, to oh golly gee we are not alone, and these folks have tech we don't and they say there are aliens about... so this caused change some for the good, some for the bad and a desire of WLS to land grab. The WLS was isolationists because like Thesus they knew their HW system had been destroyed but had decided it was caused by not enough structure in civilian society at the time, the ship's crew believed a more structured approach to the colony was the only way to survive, so a Monarchy developed out of that with a very rigid, traditional way of doing things. The Clarion way is the right way, the civilized and educated way. I then decided Clarion/Gollywog has these two names because there was a small Dralasite Colony on the planet when the Humans showed up, the Humans did not realize this at first but once they realized this they reacted poorly and wiped the small colony out and I mean utterly, when the second wave of Dralasite Immigrants showed up in the big Sphere ship WLS attacked with everything it had, the ship escaped but not before being severely damaged and ended up at Fromeltal (a previously probed system) instead, the ship's data banks were severely damaged and a lot of information was lost except that Gollywog/Clarion had been it's destination with all other data about Gollywog destroyed (so no information on a colony), and the ship's passengers having amnesia from being in cold storage so long no one but the Clarion Monarchy today knows about the genocide. Clarions get upset about Gollywog as the average citizen only thinks the Dralasites are trying to unjustly claim their world and take what is not theirs as humans where there first, the truth is their ancestors were not first just more numerous and decided to murder to gain claim.  The WLS today does not want to conquer the stars and has found being a good neighbor far better than isolationism but it would kill to keep the secrets hidden of the past misdeeds of the Monarchy/Early Colonists. There is are other secrets too the Monarchy keeps hidden like the Charter outlining the Monarchy system was signed at gun point by many settlers.

Thesus System on the other hand took a completely different approach, they decided the rigid ways of military thinking had caused the destruction of the HW. So they went for liberty, peace, love, arts (thus the entertainment focus), and ideas they felt would make for a kinder society they desired a new way. They hoped and dreamed other colonies had survived, they hoped to some day find other human colonies, they knew Lux was headed to another system near them, so they worked long and hard to rebuild space technology and develop communication technology to find the Lux Colonists but instead they found aliens. Instead of being threatened they embraced the other two races, but also realized they needed to colonize too. 

So Thesusians & White Lighters are very different yet Human each group has biases good & bad, I also decided they speak different Languages. White Light & Thesus where not able to really build empires so to speak but spread a mix of their cultural ideas as knew colonies formed, though I think WLS wanted to unify the Human Colonies and that was probably one of their goals. Thesus was more colonize and trade but not into a unified control approach. With the Sathar War came a massive change in goals for the 2 oldest Colonies... Thesus was suddenly on board with some sort of unifying body (but for all races) when before they where all don't tell us what to do and WLS junked it's ideas of being the only Human government and keeping those nasty other 3 aliens out to yes oh yes we need allies not just trade partners and maybe we can all can get along, co-exist and we are cool with a Council of Worlds we are not in charge of, so changes in foreign policy for both governments. Anyhow that is my thoughts on the 2 oldest colonies in my setting's background. 

Basically PF time is not happy get along time it is a mix of good & bad, conflicting agendas that lead to conflicts, the humans colonize to either be territorial (WLS) or for building trade (T), both are a sort of empire building. The Yazirians are busy building their little empire in the stars and trade because they need extra resources. The Dralasites seem to have other interests and are moving slower maybe they were still trying to figure out where the heck they came from and where to go from what little info they had. The Vrusks wanted profit so they were eager for trade and want to build financial empires. So conflicts where happening between all the parties, cultural, territorial, racial, and financial.

I think the Dralasites somehow became the glue to bring about cooperation, but if the modern Dralasite population found out the truth of what happened at Gollywog it might damage severly relations between races and or cause problems for the WLS Government.

 

 

Each came about for roughly the same reason, something was needed to unite the people against the enemy. So the thinking would be that the human cultures had differences on their planets but when aliens were found or maybe to go and find the aliens one culture took dominance and that is the one that is generally thought of.

One example would be Mexico. While most of the planet thinks of Mexico they go with tacos and hairless dogs and really big hats those really only identify part of a vast country with many different cultures and attitudes.