@KatherinWinterWell, he doesn't
want to be on Earth, this is just where he crashed. Since he can't get back, and he doesn't have any where else to go, he may as well stay here. Plus, the fact that Earth is primitive by his standards gives him purpose. He has things to upgrade, things to repair. It also provides him with something he's never experienced, learning. He knew everything he'd ever need to know from the start of his life. Now he's stranded on an alien planet that operates by completely different rules.
He is kind of limited in his thinking. His thought processes are very rigid and structured, but that's one of the things that makes him feel less human. He's practical and logical, but not very emotional. He's not devoid of emotion, he gets frustrated if something he
just fixed is broken, he feels satisfaction knowing he did a good job, etc. He's kind of supposed to get more human over time, which is maybe why he was put on a team, instead of just being kept around to fix and upgrade stuff.