If your character’s starting off at level one, they’re really only getting started with adventuring. You can let that be reflected in their backstory.
If you want to play a badass, starting above level 1 is allowed, though probably not recommended for new players still learning the rules of whatever system you’re playing.
To be fair, if I was aiming literally anywhere else but down at a rat crawling over my foot, it probably would have been a misfire or a bad ricochet.