Beginner Character for OW?

I wouldn't say a 'beginner' hero, but I'd tell you to try out all the heros in the practice mode, as you can see what kind of playstyle you like and abilites; whether you like being more of a Tank, DPS, or Support. You shouldn't be too focused on a specific character, but do try to learn a hero from each role too keep things fluid when the other roles are taken.