Captain America is Marvel universe, lol.
Historically speaking I don't think any nation has fought with thrown shields, as shields are designed to be defensive.
From an offensive perspective, I can't see them doing more damage than arrows regardless of how aerodynamic you make them, as they are generally blunt where arrows are piercing, and their extra weight would make them fly slower at higher energy cost, at best I could see them do heavy club damage (1d10+2)
"you are the only cactus in the garden of my life" Gomez - Adams Family