>>96261941 (OP)Dunno about others, but as I have a lowish kind of fantasy setting, there are a few reasons than humans are dominant. First and foremost, humans are Smart, reproduce easily and can live in lots of biomes, and live long. Other humanoids are either dumb, slow to reproduce, too adapted to they biomes and/or have fast lives.
Another big one, humans are one of the few humanoids than Sweat. So they are one of hte few than can use heavy armor, and are incredible enduring. Other races can be bigger, stronger and have other advantages, but be sheer durability, humanity can out-fight nearly anything via numbers or tenacity/stuborness. Another big one, humans can throw things, other races barely can use weapons than aren't adapted to them, and most barely can use crossbows, better to not talk about throwing spears, rocks or using slings.
The average human warrior of my setting is more like an imperial rome legionary (tough far more tribal), using heavy javelins to pierce ogres, darts to break goblins and big shields and stabing swords to herd and slaughter orcs if they survive various projectile volleys .