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.
Or play Exalted, initial Chargen gives you an initial badass.
I still maintain DND is kind of a bad first rpg. It's extremely idiosyncratic in its rules, and it's also a dream crusher that squeezes the creativity out of new players.
More people would be happy with Fate.
That'd do it. White Wolf's Scion will do it too. Or Eclipse Phase..., really, there's a lot of systems where you start off as a badass.
None of those systems we've named have levels, though.