wait but why do we not play as the human from adastra?
Because it's the next stage of the story, it's a continuation which means it is a sequel, it doesn't have to be through the eyes of the same character as before. ^^
My theory is that while things are being figured out on Earth by Marco, we get to see the Political environment and plot thicken in Khemia with Scipio and Neferu to start having things get crazy! :3