Overwatch: Learning Offense at the Training Range

I just got Overwatch yesterday, so I'm in the middle of trying to learn the game. I'm going class by class in the training range to see which one I'm better at as well as which character in that role. For the first training session, I'm going with the offense class. As I have a feeling this will most likely be the class I stick to.

What is Offense?

Typically an offensive role is to be the scout, harass the opposing team, and press the objective. You're in the center of the battle the mass majority of the time. Heroes have high damage weapons and abilities, but have lower health pools. Each character is highly mobile and good burst or sustained damage from what I gathered in the training grounds.

Who are the Heroes?

Offense Heroes Overwatch

The offense heroes are the following as the appear above: Reaper, Solider: 76, Pharah, Genji, McCree, and Tracer. There will also be Doomfist but I haven't unlocked him or he hasn't been added at this time. I also somehow forgot to include Sombra when I was taking these screenshots from the game. The easiest characters being Pharah, Reaper, and Solder: 76. Medium being: Tracer and McCree. And the rest being the most difficult. But to be honest, I prefer those more. Out of all the characters in this class I can see myself playing as Genji, Sombra, or Tracer the most. Mainly Genji.

If you play Overwatch, who do you play as? Also I would love tips!