Men were the second race to be created after elves at the beginning of the first age. Being the second race gave them the name, Hildor (aftercomers). Unlike the elves, humans were not immortal or immune to disease. This gave them the names, Firimar (mortals) and Engwar (the sickly). Unlike other races, men warred among themselves, instead of uniting. There were many different “tribes” with different cultures. Some the the prominent humans were, Aragorn, Arathorn, and Boromir.
I did not know all of this, so please check out my references.