This doesn't really respond to the bulk of my post which focused on the differences between pregens and Origins. Again, even in these PnP pregens, their written backstories aren't as intrusive as Larian Origins who have more of a defined arc during, not just before, the game. Larian Origin characters are made so you play through and experience their story (SH & Shar, Lae'zel and the gith, Gale and Mystra/bomb, Wyll and his devil), whereas pregens typically provide a starting point but then allow freedom during the game.
This is especially true for SH, who has an in-game backstory that you - the player - don't really even get to know. You discover it during the game, but this is again playing through SH's story and learning who she is, as opposed to making her character your own from a set starting point.
I'm not really sure what point you're making that hasn't been addressed multiple times throughout the thread.
If anything, all of this means it's better to play an Origin character. Instead of a typical blank slate with a "chosen one" nod, you get to play an actual character with an actual back story. Sounds exciting!
As for the character's free will, of course you'll be able to make choices for the Origin character during play. There'll still be conversation choice trees, and you'll still be able to pick the option you want. It's not like the whole game is going to turn into a movie once you select your Origin character.
Like I say, I'm not reading anything new here. All of this has been addressed, and I even mentioned how pregen characters are often more complete in my last post, which you quoted.
