Now, I've seen threads that focus on this in obviously larger ways, such as "Neanderthal New World", but that isn't quite what I'm looking for. To kill most of the possible butterflies, and to keep history going as per OTL until fairly recently, let's say a significant population of Homo erectus survives on some isolated Indonesian island. They are hairier than us, shorter than us, have a somewhat more ape-like face, and still live in a Stone Age culture.
They are discovered in the late 1800's by Europeans, perhaps in the expeditions started by Eugene Dubois to find a fossil of the missing link between ape and man. What is the effect on human thought of having a biologically distinct separate species of human still alive during the present day?