I have to admit that this scene surprised me. But I didn't think about it in the way some people obviously did, because, just as has been mentioned, the MC from Last Human and the MC from Serenity are basically one person. That's too obvious just by looks, and has been mentioned in the game after the first time Rin appeared, if I remember correctly. She returned to Serenity, and I think it was the MCs mother mentioning it.