History is told by the victors. The traveler is only good because we say so. The "story" of this game is so vague that it leaves anything to speculation. Also, the speaker is very mysterious and cryptic and doesn't clarify much. How can guardians be the "good guys" when they slaughter leaders of entire races and farms the remaining ranks for weak weapons and armor? It's ok to believe the traveler is good… but like MattPat said, what alien species would help out humans for nothing in return. Also, why would the traveler help out earth if it knew devastating forces tailed it throughout the universe?