Grimoire cards is where I get most of my info, and since the Destiny story is finished, everything that happened in it is canon. If they worship darkness, I'm pretty sure that means they're dark. And i don't remember where I read/heard about the fallen attacking us first. Let me find it. But that said, the Fallen came to OUR planet.

You're still working on the assumption that dark is evil. Bungie could be switching it around to show that good and evil are a matter of perspective. The Fallen may also be on Earth because our enemies (possibly even the Traveler) had already banished us to the city. From what the lore tells us, it doesn't sound like only the Fallen caused the entire collapse. Maybe the Traveler even caused it. The lore does mention, however, that the Fallen and other enemies appeared on our former planets AFTER the collapse. They could simply be scavengers who found empty land.

When I say darkness I'm referring to the Hive. And Darkness is evil. What else could the darkness be? Destiny's lore and story was created in about a year, if not less. Activision forced Bungie to make cuts so that they could get the game out quicker. I forget his name but one of the guys leading the story creation quit because he couldn't include all his ideas and background that he had been working with. I'm such a rushed amount of time, I doubt Bungie was looking too deep into this.