My everage on widow is 65% but I have over 100 hours on her. But I think generally for hitscan characters probably over 50%. But it’s very dependant on the map and team comps of both teams
I only remember my Accuracy with 76 and Ana.
Soldier 76: 38% in all modes with 850+ hours on him. The more you play, the more it goes down-. Average I get is 45%~55% in-game, when playing seriously dealing good damage. I assume you indeed need to work woth your tracking on him.
Ana: 65%, at least, unscoped. 75%~100%, scoped. I barely use the scope, unless I have the clear shot landing, for sure.
Usually enemies have certain patterns that are predictable. E.g. Going for a healthpack, objective. A healer will obviously run to injured teammates. The only tricky part (that's what I have trouble with) is to stay somewhere they don't see you or have issues hitting you. Then you flick and aim for the neck.