In my high fantasy world, Humanity ascends to create magic and is later collectively reincarnated as beings called Thaen, (plural of Thane), which are basically human beings with the power to manipulate magic. The first few to rise were visited by an Archon, (basically an elven heir to a god), who instructed them to remain and rally the Thaen as they continued to emerge. Thus they become nobility. One of these first few, Isodd, was shortly joined by two children. One child's skin was fair as ivory, the other's dark as onyx. Isodd called the two children his sons, and raised them to carry out the Archon's quest. Creth, the eldest and fairest son, heeded his father and vowed to fulfill his mission. Knoth, the unruly younger sibling of darker countenance, was stubborn and proud, and would not kneel before his father or heed his foolish tales of divine visitation. When the children had grown to young men, Isodd wed another of the first risen and held a joust between his two heirs at his wedding ceremony to determine which would succeed him. Creth won the joust and was dubbed Isodd's true heir, and Knoth was bound to a vow of squireship. The two children known to legend as "the Knight and the Knave" later became the progenitors of the Crethaen and Knothaen people. The Crethaen are taught from birth that they are destined to reclaim the world and redeem humanity, and that their Knothaen counterparts exist to serve them forever in atonement of their forefather's pride.

Just one example of racism in my world. Inspired largely by the tale of Nephi and Lamen/Lemuel from the Book of Mormon, (thanks but no thanks to Joseph Smith for his world building), in which the Lamanites are cursed with dark skin for being less valiant in the previous existence.