Clint_L
Legend
There are many shorter lived sapient species, though. Why aren't goblins mostly running the show? Also, some of these assumptions really vary by setting. On Exandria, Elves are longer lived, often attaining several centuries, but nothing close to immortal. Even in AD&D elf lifespans were measure in hundreds of years, not thousands.Compared to the other major peoples of the Material Plane, humans are...
Short-lived. Their lifespans are slightly shorter than those of halflings, much shorter than those of dwarves, and like the blink of an eye when compared to the (near) immortality of elves, which is related to...
Again, this is setting dependent. There's no particular reason that humans should be ascendent, other than that has often been the case in fantasy novels and D&D settings. And the "other people in decline" trope comes mostly from Tolkien. It's not really still a thing in D&D, if you look at the descriptions of various species in the rules and settings.Ascendant. Whether due to their faster breeding cycle, a natural inclination towards expansiveness, or the workings of some divine plan, humankind are in the process of achieving dominion over the world, while the other peoples are in decline or will be imminently.
Edit: sorry, just noticed that your avatar described you as a "Dungeon Master of Middle Earth." Sure, in that setting your observations are on point. That's not a D&D setting, though.