And just to nitpick, I'm guessing a level 1 fighter hasn't mastered every type of weapon as I assume that is why we choose our specialisations as we level up?
Fighters have proficiency in all martial weapons, which means they're trained in their use and can fight with them as well as any trained soldier. They further specialize in specific fighting styles in the form of Fighting Style choices, but even if you specialized in Great Weapon Fighting you're still as trained (proficiency bonus) in the use of a longbow as your resident rogue sniper is.
Fighters are masters of war who can pick up any weapon and fight effectively with it, but reach a new height of deadliness in a specialized style of combat. Even a 1st level fighter is meant to be a hardened combat veteran, a trained bodyguard, or a royal knight in the court of a king.
As contrast an actual nobody with a sword would be similar to a bandit, which has a CR of 1/8th. Which means it takes eight bandits to be a moderate challenge for four 1st level adventurers.
As for if the game wants us to see ourselves as nobodies or somebodies, I think the intro resolves that pretty easily. We see all around us dozens of bodies of normal folks who've been mind controlled by the Mindflayers and torn a part by imps. They're laying on the ground bleeding out as we march through the ship, weapon in hand, cutting through the imps and fighting our way to the controls.
We're clearly supposed to be someone exceptional. Someone that can earn the respect of a Githyanki pirate or a 200 year old vampire spawn. We go on to lock blades with ogres and come to blows with evil hags and flesh eating gnolls.
I dunno how much more clear the game can be that we're not average folk. We have a set of skills and abilities that make us exceptional, and that is why we're able to escape the Nautiloid ship in the first place.