This is a very fanciful version of evolution. We have talking animals and a proto-human who has become human by many measures all at the same time: getting hairless, thinking, walking erect and tool-using.
But, both he and the animals around him are talking, using language, and talking across species, so this is mostly a parable.
This first human lives in the jungle, ala Tarzan, rather than on the savanna. This is an Edgar Rice Burroughs contemporary image of man/ape lifestyle.
Yup, new style thinking is hard. Analytic thinking. <grin>
Curious... there doesn't seem to be that much innovative about this story. This is about a near-monkey thinking through tactics and using tools to help a combat tactic. All I can conclude is that the concept of animals learning... other than teaching a dog tricks... was not well accepted in outside-of-the-farm circles. ...but this seems strange. I'm sure farmers were well aware that animals learn, and a whole lot of people in the 30's and 40's grew up on farms. So why is this story considered innovative? That is a mystery.
Ah well... his description of the lion attack mid-story is belief shattering.
o He isn't willing to give up his club, even though it's just a piece of wood he found earlier that day? He can't replace it virtually instantly? He doesn't think he can?
o Lions are ambush hunters, mostly night hunters. This confrontation takes place during the day, and in "High Noon" fashion.
o He swings for the ribs, and then the densely fur-covered neck. That fur is neck armor, bad choice. He doesn't realize this? This is instinctive knowledge for any animal that deals with lions, including lions. He is surprised that a head-blow gets results? ...sorry.
LoL! And the story ends with him being a classic cave man, with a submissive woman slung over his shoulder as he heads off to start his new home.
Ah well... This story is only significant if it's the first popular one of its kind -- similar to the first Frankenstein, King Kong, or Dracula stories. If so, this is the inspiration for the introduction scene in "2001: Space Odyssey", as well as thousands of cave man cartoons and comic skits. And if it's the first, it's interesting how completely it has been forgotten -- how unlike Dracula or Frankenstein.