Rey certainly demonstrates natural innate ability to use the force (i.e. outstanding pilot, reading Kylo's mind/feelings while resisting his mind read, Jedi mind trick on th first order storm trooper, evading stormtroopers on Starkiller base, out dueling Kylo with lightsabers). It would also seem that Kylo had never before met Rey, which, if she was somehow related to Luke, would be unlikely.
If you may recall, Kylo was able to see in her head visions of loneliness, oceans, and an island. Fast forward to the end, the secret Skywalker map takes her to a planet with oceans and islands, a place where presumably Luke was searching for the original Jedi temple. Perhaps she is a descendant of the first Jedi?
It would be easy to say that Rey is a Skywalker or a Kenobi. But her story will actually be more complex. Whatever it is, there will be some sort of connection between Luke and Rey, as Maz made reference to on Takodana, that Luke would be in her future, and that she had to let go of the past and hope that her family will come back to Jakku to get her.