i will argue that the player character has nothing to do with TES lore, since our roles in it are limited to what the devs say we did and we are always subsequently erased from record.
The very first words of Morrowind would already disagree with you:
"Each event is preceded by Prophecy.
But without the hero,
there is no Event."-Zurin Arctus | the Underking
Also, I'd suggest having a look at the 36 Sermons, with special regard on "Ruling King".
Edit:
The Nerevarine going to Akavir is what it is: a rumor. Nothing more. There are no definite passages which mention what/or that something happened to a hero of any of the games, with the exception of Cyrus, of course, but that one is a definite person.
Your "point" of doing anything you want is somewhat moot. There must be something basic thread which drives the story further or there would be no story at all. That's why the "main quest" is fixed as to what concerns the outline of what happened. However, so far, no one has mentioned any specific details on what exactly the hero did besides fulfilling the respective main quests. There is no mention of the hero joining guilds or anything, so that is up to the player to define.
What I said above is backed up firmly in accompanying lore, the most obvious would be:
"a prisoner born on a certain day
to uncertain parents [...]"