Well, not you in particular, but all of humanity. According to a new Q&A with lead designer David McDonough and Will Miller, the game's story is one of redemption. After destroying our planet through wanton greed, pollution and just generally being a ravenous, bipedal blight, humanity has decided the only way to continue our species' existence is to blast itself into space. Specific details of this mass diaspora are scant, though the Q&A does mention something called "The Great Mistake" which the designers describe as "a mysterious event that is partly interpretive to the player." Based purely on the name, we're guessing this Mistake wasn't a choice to pair red wine with fish.
As a result of this wholly new setting, the Civilization: Beyond Earth design team had to create a new universe of technologies, lifeforms and extant cultures. The designers cite both modern and classic sci-fi as inspirational to the project, and specifically name such genre luminaries as Isaac Asimov, Arthur C. Clarke, Ray Bradbury and Robert Heinlein among key influences.