As I’ve stated before when this has come up, she’s looking for for her place in the world. At first she thinks she’s looking for someone to show her her purpose, by the end of TLJ she’s coming to understand that she’ll find her purpose on her own. Everything she does comes down to that and her innate goodness (which are connected, she longs for connection and is isolated but empathetic - look at her saving BB8, empathetic to his plight and ultimately finds kinship with him). Even without building the new Jedi she has still found the place she was looking for with her friends in the Resistance.
Her innate goodness is the problem I have with her. It’s stagnant and boring to me. The combination of innate goodness, and recieving powers from on high removes all chances of development, and choice. She doesn’t choose to commit herself to the hard life and sacrifice Qui-Gon Jinn speaks off in TPM, she just gets bestowed with these powers, and has to deal with it. She doesn’t choose to do the right thing after having faced temptation, she immediately does the right thing, because of her innate goodness. The growth in her character is severely limited by the fact, that she’s already ahead of everyone else morally and in terms her abilities pretty much from the get go. The story of Luke is like the poor guy, who through hard work, struggle, and sacrifice builds his fortune. The story of Rey is like the orphan girl who wins the lotery, and now we have to witness her “struggle” to spent all that money, that she immediately spends wisely from day one, without ever losing control like a normal person would.