Otherwise how are we supposed to know that middle aged man is the fresh faced young man in the earlier films? I know the whole film is about finding out where Luke is - not sure why - but, by that time, many will have fallen asleep and only woken up by the music over the end credits.
How many air-breathing beings do you think there are on that planet? Yeah, it's an entire planet, but one that offers, well, a couple of acres where humanoids could live without serious technology.
Assuming that the first middle-aged male human she saw who was wearing Jedi-style robes was Luke, was reasonable.