So here's the thing: Any "origin" you put on a player character, will take away from your agency and your ability to roleplay just as you like. Any background that actually has a story, locks you out of being a blank canvas to put yourself on.
I get where you are coming from, it's difficult to feel you are anything at all when the game starts very in medias res. For all intents and purposes we were born on the Mind Flayer ship. We have no knowledge of ourselves, that's both a boon and a bane. The boon is that we can project whatever personality on our character. That's true roleplaying. The bane is that we don't know ourselves at all. We have no connection to the world we play in.
Baldur's Gate 1 was more of a hero's journey opening. We start in a calm town, where we existed for many years. We Existed, but didn't matter, until our adopted father comes and say we need to go on an adventure. While we have less ability to project our ideas onto the character, at least he's grounded.
I'm the sort of player/DM that prefers a backstory be in the background. The character wasn't supposed to be anyone before they are thrust into an adventure. Sure they existed, they lived, but they weren't a hero. The great thing about a backstory at the table, is it's free and adaptable. The DM can adapt to your story on the fly, and you aren't limited to what the DM gave you. The DM can set the boundaries. He CAN say you are from Baldur's Gate, but not what faction you belonged to, or who you knew.
One problem I often have with games that has a predefined story for the main character is that it sometimes push you in a direction. It can of course work, many games does it well, but I don't play "Player Character" at that point, I play "whomever the game creators had in mind".
I did like Dragon Age Ortigin's background selections, it's probably something like that I think BG3 should have. Dragon Age 2 was a little too "Mass Effect" for my taste, you had less room to define your character. Dragon Age Inquisition sort of does exactly what Baldur's Gate 3 does: Starts you In Medias Res, and you become special because you are given a weird power.
