The People That Time Forgot is a short, fun story. At first, I felt that it was another typical Burroughs story: strong male protagonist, exotic and beautiful woman who is also rather capable, yet needs saving whether she knows it or not, less manly antagonists that fall fairly easily, and an underlying theme of evolution and the ties between man and animal.
I guess I still feel that way, but additional thought helped me realize that there are a lot of fun themes to be discussed here. Such as: What if evolution occurred at a rapid pace in an isolated location? How would the plant, animal, and humanoid life-forms look and interact with each other? What is a savage? What is love? Is love a choice? How much should societal norms play a role in our choice of a spouse? What are the concerns regarding relationships between those of different races, cultures, belief systems, financial background, etc.? Are these concerns valid? If I answer no, am I basing that answer on principle or contemporary cultural norms? If the answer is yes, to what extent?
My final question is: why am I too lazy to dig into these questions any further than my casual wandering thoughts during my commute to work?
In short, if you like Edgar Rice Burroughs stories, give this one a read or listen (preferably after part 1).