I think I'll wait for the GM's thoughts, mate. They mentioned aliens were alright, and I've got ideas for a backstory to explain how he got to where he is. Forgive me, but as another player you have no grounds to tell me to reconsider. If the GM asks me to, then I will, of course, but you have no right to tell me what I should and shouldn't make.Not the GM, but I'd strongly reccommend against this, since this brings up several questions that complicate everything else.
I've been in private talks with the GM the past few days and the technology level doesn't allow for inter-galactic travel between galaxies, it's a chore to go from one end of the empire to the other (months), and this isn't a galactically sprawling super-empire. The space between galaxies is several magnitudes larger still. This would be extremely difficult to justify and if there's other civilizations in the universe with intergalactic travel, they would presumably be common to encounter in some sense due to that factor.
Further, he has shown interest in expressing the 'alien-ness' of the alien invaders more strongly and has suggested he'll be retconning out the mention of alien species. This will move the context of the aliens to be the first aliens ever encountered by a human race in a 'space-rome' type of civilization, making it more of a cosmic horror story in nature with a lone humanity in confusion after a disastrously violent first contact scenario.
As I said, not the GM, but from what I know this isn't congruent with the overall plans of the GM as I know them, please re consider.
Thank you for your time.