To me Mercy is a beginner support hero in the sense Reaper is a beginner DPS hero. They’re both super-simple to use without mechanically demanding kits requiring strong aim (Reaper literally just needs to be in the enemies face and shoots, Mercy holds lmb/rmb to heal/dmg boost).
It sounds simple but it’s honestly true, if you find a hero ‘dull or boring’ then try a hero (in your preferred role) with a more mechanically demanding kit. McCree/Soldier is to Reaper what Ana/Zen is to Mercy.