In the cosmology created by Tolkien, there was first Eru, who created a great Music which manifested as the Universe. The Song included strains and themes that manifested as the Powers, and Eru made them the lords of Arda, tasked with preparing the world for Eru’s First Born.
One of the Powers, however, in his eagerness and impatience, created a people of his own– the Dwarves. When he came to understand Eru’s intent, he offered to remove his own creatures, but Eru would not allow these living, knowing beings to be destroyed, and granted them the right to carry on, as Dwarves are famed to do. But the Dwarves must sleep until after Eru’s own first children waked.
Last, Eru put Man into Middle-earth, and as this part of the Great Song came after the Powers had come to Arda, none of them knew how this theme went, and so Man and the destiny of Mankind is unknown to them, and Eru’s purpose in creating Man is a mystery to them, as well.
— to be First Born, to rise and stand,
the earliest wanderers in the land
–to master every kind of speech
–to awaken, name, and teach…
–to live forever in glowing grace,
lithe of form and fair of face
–to own kinship with the very bones
of mountains, metals, gems and stones
–the mastery of smithy-art
–strength of limb, firmness of heart
–to be as solid as Middle-earth
–to live long lives and value mirth
–to come to the world the least of all,
with fear and doubt, and prone to fall
–to struggle for life, to fight for learning
to reach and reach, forever yearning
and after all, the gift of Death
to bless his every living breath
Elves and Dwarves were the first holy sending
but Man-kind will last until the world’s ending.