Because Kipling didn't retire to a ranch in California?
Mowgli didn't fight the Ant Men or go to the center of the Earth, either.
Seriously though, Kipling's Mowgli is superior in a literary sense, but Tarzan is King of the Jungle when it comes to the Pulps. Plenty of period racism in Tarzan as well: Gomangani vs the Tarmangani.