Point of order, re: Tolkien’s humans. Yes, a fallen race. Yes, given to restlessness and waywardness.
But no one, certainly no elf or dwarf, achieved anything comporable to what Beren Erchamion achieved, excepting Luthien, his elvish wife. Beren successfully wrested a Silmaril from the crown of Morgoth, after having invaded Thangorodrim–a place that makes Sauron’s Barad-Dur seem like a straw hut–and endured innumerable horrors. To be sure, he had Luthien and Huan helping him! Huan was a mighty wolfhound capable of kicking the crap of out of no less than Sauron himself (albeit Sauron pre-One Ring); his loyalty to Beren was unquestionable.
Beren’s and Luthien’s eventual offspring, those who chose a mortal life and thus chained their fates to those of men, were the Numenoreans. Aragorn is a distant descendent. The fleet of Ar-Pharazon was so magnificent that the horde of Mordor fled in its face and Sauron himself surrendered to them. He intended further mischief, to be sure, and succeeded to no trivial extent. It is clear though that he knew he had no hope of defeating the Numenoreans in battle.
Even in the Third Age, it is apparent that all the free peoples of Middle Earth depended greatly on the descendents of Numenor, particularly Aragorn, to survive the increasing darkness wrought by Sauron (and Saruman). And of course, unbeknowst to them, on hobbits. Still, the central role played by the Dunedain and the men of Gondor is unquestionable.
Humans, a mediocre race? I don’t think so. Read Tolkien’s chapter on Turin Turambar from The Silmarillion, not to mention Tuor, for further evidence.
[/Tolkien nerd]