Orcs were invented by Tolkien as a type of souped-up goblin so all trace back to that. Which makes them monsters.
Dark Elves come from Norse folklore. The Ljos'alfar (Light Elves) & Dökk/Svart'alfar (Dark Elves). I'm not disagreeing that D&D helped solidify the modern conception for most fantastical creatures but they took inspiration form 100s of different media forms to help create their game.
But my point is were not basing things off there original origin, were are basing them off the typical fantasy tropes. If you said that Everi was a dwarf just because dark elves are dwarves in mythology you wouldn't really be right. Since basically the 80s Orcs haven't been monsters but just another humanoid race same as elves and dwarves, they just happen to be a race that leans more towards the evil alignment. In modern fantasy orc are literally just muscular green humans