OK, to start with, they're not 'fighters,' they're 'heroes.' They just happen to be depicted as tougher than the Rogue class would support, and don't cast spells, and don't go berserk on a regular basis. They're Fighters by default - the fault(pi) of the system.
In an entirely different sort of RPG system, you'd give a hero like that generally better stats than the sneak or mage or muscle-bound barbarian, and a lot of skill (in combat & out) - and no particular magical powers or supernatural abilities. If 5e gave the fighter more high stats than other classes at first level, an extra skill every few levels, an honor/reputation track, and expertise here and there, it might start to look something like a character from genre.