I also think the discussion is getting a little bit sidetracked with how the continuity of the quests go with in the first place. I understand that they take place in the past. I can accept the flashback explanation. The ONLY issue is that the tutorial seems to be the adventurer's first experience as an adventurer, yet it takes place in the 6th age. This isn't about the continuity of any other piece of content, so let's please not discuss that as that's not what I want to talk about.
The events that occurred during The World Wakes and all quests that take place prior to it have happened in the past, whether or not you have played those quests. This is the reason every single player was able to play through content such as the Battle of Lumbridge without first completing the quests that led up to it.
They have done this so that every player is at the same point in the game's timeline, no matter how many quests they have completed. This allows every player to participate in content such as the world events, and allows Jagex to do so much more with the sixth-age content.
This isn't anything new, Jagex has explained this multiple times already. They even posted a news post about it shortly after The World Wakes was released, stating that The World Wakes and all content that took place before it is now in the past, whether or not a player has actually played through it.
This isn't any more of Buy Runescape Gold a time paradox than when you watch a movie then watch a prequel that was made later. Even though the story in the second movie takes place before the first movie, it still makes sense. The prequel movie just adds background story to the events that occurred in the first movie.
As for the Ashdale tutorial being our first adventure, I don't believe that is supposed to be true. I don't think our characters were born there and never left, that is just where we are at when the story begins. They can go back to events that happened earlier than that via quests to add more background story, though.