In that sense, companions take their twelve True Soul (class)-levels which kind of clicks with D&D-rules. Since this paradox exists in so many level-based game systems, where you're supposed to be the chosen progeny of the ancient half-alien-jedi-dragon prophecised-saviour-of-the-whachamacallit, but then get your guts handed to you by a low-level enemy at an early stage, I'm really glad Larian avoided that jaded amnesia trope. In my head-canon, Wyll still went to Overnis in Tethyr and battled ankhegs by the River Ith after the end, though. That's where the explanation stops working for me.

I still have a half-written AD&D-campaign in my drawer somewhere in which players start as 0-level just noticing something is odd about reality and become the only beings in that setting that have class and levels while working their way out of the scenario. Perhaps I should dig it out again.