I've seen posts of users discussing what the story of Journey actually means, what the conflict of the story is and why the Traveler is attempting to reach the mountain. I personally think that's looking at it the wrong way. I originally attempted to understand the story in that manner and all the answers I came up with were very vague. Then I thought, "If this is an artistic game, why am I trying to understand it like an episode of "Lost" or a game of "Call of Duty?" I realized I had to think about it in metaphors, rather than a coherent storyline. For example, the ending of the Journey, where the Traveler returns to the beginning of his/her quest. If I were trying to think about it like a storyline, it would make no sense, because that would defeat the point of reaching the Mountain. But if I think about like a metaphor, I realized it could mean a representation of life, death, and rebirth, the "Circle of Life". In another example, the Companions. If I were in the mindset of a storyline, it would make no sense for a character to simply appear at random and then not be able to communicate with the Companion and be able to abandon that person at will. But when in the mindset of a metaphor, I realized the game was trying to communicate that the "Journey" of life is much easier when someone is there to share it with you and that the paths of all of our "Journies" can diverge at any point.
But of course, the only thing I want more than to share what I think, is to hear what you think!