Balance of the Force has been a theme throughout the saga, particularly in the prequels. I don’t know if anyone noticed but the round pool near Luke’s special rock seemed to have a balance symbol, rather similar to Yin and Yang.

I actually thought The Last Jedi gave us a really nice, naturalistic, presentation of the Force, and went a long way to retcon the mistake of Midichlorians, blood tests, and ‘all in the genes’ exclusivity that the PT advanced.

Rey isn’t a Skywalker, she isn’t a Kenobi. She’s no one. And for the audience, that makes her everyone.