Similar things can be said for Kipling's "Just So Stories". I simply explained to my kids that the way people treat race now is a lot better than back then. Just as they were wrong about what they thought of space travel, they were also wrong about other races.
Personally, I've never understood why the anti-racist position coincides with the triumph of evolutionism. Certainly people who actually, truly believe that every single human being who has ever lived is descended from Adam and Eve can say (as did Thomas Dixon Jr., author of The Clansman [which became the basis of the film The Birth of a Nation]) that Blacks can never be equal to whites because of thousands of years separating the "social evolution" of the two. Yet Dixon was a Baptist minister (or was for a while, anyway) while people who insist that people are animals who are at various stages of development are crusaders for brotherhood. That has never made any sense to me, and it doesn't make any sense now.
I like Kipling's Mowgli stories as well. Mowgli is actually a superior character to Burroughs' Tarzan.