Human is a species of... oh come on! do I really have to explain what a freakin HUMAN is? I'm pretty sure that's common knowledge! I mean who else would read this site? an Octopus?! Well... They are actually smarter than apes. I'm, not kidding. They are! Crows are up there too. Not dogs though. They're kinda morons compared to octopi/crows/apes. Heck, even pigs are smarter than dogs! We eat pigs! Why do dogs get all this love and respect? Dogs s-ck!
In Demon Lord Dante its explained that God split his ectoplasm and infected apes, causing them to evolve into humans. Also the real humans were from Sodom and Gomorrah and are demons and demon worshipers respectively. Well, That's actually pretty creative.