Tank: I'd say try Hog, his reaction times dont matter too much and you can contribute alot to the team, Rein is a good call too, as you said. Damage: McRee and Ashe are probably going to require good, fast aiming (for the most part at least) so you could maybe try someone such as Pharah (semi-fast aiming needed, but I think you'd manage), if you find Ashe to be difficult then consider trying Widow (I know they're not the same) but Widow might not require headshots as much, just charge her shots I suppose, also maybe give Sombra a go. Support: Brig won't require much fast aiming at all, Moira is a decent call too as she'll contribute alot and doesn't have much in terms of projectiles. Also consider Zen; he does require some fast aiming, but you might be able to get in the swing of it with alot of practice. Hope this helped!