To help with the character lore a bit:
Almost all of the backgrounds assume you are from Baldur's Gate or the surrounding area, so we can focus on the latest comings and goings there. If you decide to be a folk hero, then you could be someone who lives on the outskirts and mostly just helps people out with their lives (and gardens). Not all heroes wear capes. Being able to create food for people, along with all the other benefits to some of the basic healing spells you have access to really would feel heroic to the local peasants. Far more helpful to them than a fireball or icebeam.
What has most recently happened in the BG and it sister city of Elturel is:
About a decade ago the last two kids of an evil god (Bhaal) killed each other and brought him back to life. The city was torn up a little from the fight and left in disarray politically because one of the god's kids (Abdel Adrian) was the leader of Baldur's gate.* This is probably something you would remember and depending on your character's age you may have been around to help some of the survivors.
Eventually things settled down and Abdel's prodigy, Ulder Ravengard, took over as leader.
Cut to a few weeks ago and things went crazy in Elturel. Basically their leader tricked Ulder into visiting for a diplomatic discussion. However, it turns out that Elturel was traded to an evil demon with all the people inside of it. The whole city descended into Hell with Ulder in it, but somehow it was saved and returned to the real world.* Ulder is on his way back to Baldur's Gate when the game starts as are a bunch of survivors from Elturel. A lot of tieflings are fleeing the Elturel because of their demonic blood now makes them a target for racism since the city was nearly destroyed in Hell.
At some point you were abducted by mindflayers and wake up in one of their ships. That is where the game begins.
Hopefully that gives you enough to start with

*Those two events were captured in the DnD modules "Murder in Baldur's Gate" and "Descent into Avernus" which are made pretty open with many different possible endings. This is why no one really knows what happened in the BG3.