I finally sat down with this a little bit yesterday. I tried each character in the training area and decided that I like Symmetra the best. Did a quick play match and we had to defend a car or something, so I just laid little turrets out and wound up with play of the game. But in other maps, I was getting taken out in a hurry.
Do people main one character, or one character of each type, or is it just best to be proficient at all of them? I never expect to be top-tier in this, but I'd like to do more than run from the spawn point into someone's bullets and at least be of some help to the team.
I'm pretty new too. I'll give you the d/l as a fellow newb (been playing...1 month?).
If you are interested in just playing Quick Plays and Normals, I'd try to just learn 5 or so characters from 2-3 roles so you can switch to something as needed ut still have some fun. Healers like Lucio and Mercy are fairly easy to learn the basics of and are often wanted, same with Tankys like D. Va and Reinhart.. I also ended up enjoying most of the Defense heroes too (Mei is bae). if you get into the more competitive stuff people WILL get salty with you if you aren't using chat, keep that in mind (I am staying away from it).
What I haven't really learned yet it what Heroes work best on which map. As a general rule, io seems to me like turret-y champs like Symmetra work best on Defense (like defending the car, or a room/point) and suck on offense cause they don't get much time to lay stuff down. I like to pick champs with a decent long range weapon for offense because I'm still learning a lot, but the actual map you are on can matter a ton. For example, some maps have famous choke points (like this hallway/stair area in the Egypt-looking stage) where Symmetra can still be good regardless of offense/defense, especially following her buffs on the PTE.
Even within similar roles (as I am sure you can already tell) champs can play really differently from each other. Even tanky champs like D.Va can have decent range, or fragile champs like Tracer have short range. Just keep messing around, when you get a bit better you might warm up to a champ you didn't like much before. Happens a lot in games like this.