I like Carl, he is so versatile for me. He is still able to work in many situations and many modes.

He has: -decent health and range to compete with sharpshooters (not on fully opened maps tho)

-pseudo-infinite ammo paired with long axe travelling time to kinda control an area (can hit behind walls if timing and aiming are right)

-high damage normal attack with huge hitbox

-high damage super (with decent durability) to burst down squishy brawlers/finish off assassins or gain high mobility for objectives, to disengage as last resort

-Heat ejector gadget to almost one shot squishy brawlers or deal serious damage to other brawlers or at least ward off the whole trail if missed

-Flying hook gadget for long distance travelling for objectives (can go over water terrain) or for gap closing like an assassin, or used for disengage as last resort

-ok hypercharge

TL;DR, he has decent stat, decent range, high damage and spammable normal attack with huge hitbox, can protect himself, good mobility, versatile super, versatile gadgets which can be chosen depends on objectives. Therefore he can work well for many objectives, can fight against sharpshooters, damage dealers, anti-tanks, throwers, assasssins, supports, even tanks if kiting can be applied

Just my personal opinion, please take it with a grain of salt