User blog comment:Varzan Deodinm Beldinm/World of Remnant... Expectations?/@comment-10390252-20140821203546/@comment-3146930-20140821212143

Of course Cortana lives in the RWBY-verse, she created it after all. After the events of Halo 4, she combines with the Forerunner system and uses it to make a planet, populating it with humans but using life-shaper technology to make humans more advanced (Aura, Semblance, and Faunus as an early experiment). Think about it, humans and Faunus have a replenishing power shield (Aura) and special abilities (Semblance).

However because of her rampant personality, when trying to make animals and such, she unintentionally created failed recreations of animals known as the Creatures of Grimm. These monsters embody Cortana's hatred for Dr. Halsey and this eventually evolved into their hatred of all humans/Faunus.