Genji
As Genji, you're the man with the plan to be fast and annoying so that the heavy hitters can destroy them while they are dealing with you. Your original fire fires 3 throwing stars in a row or in a spread to pepper your enemies with damage. Your E deflects any projectile back to it's sender. Your Left Shift moves you forward and slashes anyone in your path. Your Ult gives your melee a gigantic boost and can be used to ace a team.
McCree
As McCree, you're a coyboy with justice to serve and people to kill. Your revolver can shoot at sniper range or empty the entire barrel all in one go. Your Left Shift lets you roll and reload so you can fan the hammer twice in one go. Your E is a flashbang that stuns people so you can finish them off without a sratch. Your Ult lets you channel your inner cowboy by saying "IT'S HIGH NOON." and lock on the multiple people and kill them all at once.
Pharah
Phara is a flying bird that has a rocket launcher. Your rocket launcher is just that, a rocket launcher. Nothing different. Your E is a jump high into the air to escape sticky situations. Your Left Shift is a blast that knocks people away. Your Ult is a line of death and destruction that you don't want to be in the way of when it goes off.
Reaper
Reaper is meant to be a complete edgelord and is a total pushover in the process. His Hellfire Shotguns are just shotguns. Your Left Shift is a form that makes you impervious to damage for a couple of seconds. Your E is a teleport. Your Ult is when you shoot out all of the bullets left in your clip in a circuler manner.
Soldier:76
Soldier:76 is really just a call of duty character. His gun is just a gun that as it's Alt fire, can fire rockets. His Left Shift allows you to move faster. Your E is a heal area. Your Ult is an aimbot.
Sombra
Sombra is a hacker. Her gun is an SMG. Her Alt fire allows you to disable a hero's abilities. Your Left Shift allows you to dissaper and go faster for a couple of seconds but, shooting or taking damage will stop the invisibility. Your E is a temporary teleporter that stays for ten seconds after you throw it down but, if you press E during that time, you will come back to wherever you placed the translocater. Your Ult is an AOE hack.
Tracer
As Tracer, your job is to be fast and annoying so that the heavy hitters can destroy them while they are dealing with you. Just like Genji. Your guns pepper people with damage. Your Left Shift is a blink ahead to an area in front of you. Your E is a recall to about 5 seconds ago and reverses your current health. Your Ult is a little bomb that exploads a couple seconds after it gets placed down.