Why would he not "assume" that when humans have shaped their world so far beyond what it was, creating intricate layers of art, culture and science; even going into space or in the air? Man collectively tamed nature and the rest of the animal kingdom in a way that no beast ever has.

Anyway, this is just like solipsism, you won't find a sincere one outside the asylum. Every Reddit intellectual writing such tired drivel as "who's to say humans are more intelligent than beasts?" deep down knows the score.