Divinity 2 didn't have origin characters. There was just one mildly customizable character.
Well, they did have origin characters. Premade characters with their own background and personality and voices for in game. Like Sebille, Fane, The Red Prince etc. And you could just select their class.
It's basically the same principle that looks like it's being applied to BG3. Maybe they'll end up staying the classes they're pre-ordained to be, who knows, but the fact that they are selectable from the character creation screen(albeit not currently selectable but the options are there) that our origin characters will be able to be PC's in either future patches of EA or on launch. So you can either play as one of them or you can make your own.