Ezra can't be Ben, because we know Ezra's parents aren't Han Solo and Leia Organa, who are Ben's parents. Also, Ezra was born about the same time as Luke Skywalker.

There are a lot of non-Jedi, non-Sith force wielders in Clone Wars and Rebels, and even now in TFA. Heck, even Jeb is revealed to be a force wielder when he navigates the Ghost to his new home planet. By the end of Season 3, Chopper will be using the Force...