@deandddd , the only reason for "why not" that I can think , is that it will overturn EVERYTHING they know about their own ancient history and about the Hollow Earth !!
Also , believe me - stories such as "Tarzan of the Apes" , "Planet of the Apes" and even "King Kong" , are inspired by something that exists in the subconscious ancestral memory of humans...of a primordial time when apes/neanderthals used to interact with humans . Lord Hanuman from the Ramayan epic was probably such a humanoid being , who also had superhuman strength and extraordinary or "divine" capabilities .
Incidentally , the Sumerian epic of Gilgamesh also had a humanoid character of Enkidu who supported Gilgamesh in his adventures .
Sometimes , I think the humanoid character of Chewbacca in the original Star Wars trilogy was also inspired by humanoid characters from mythology . At some point in the distant past , humans did interact with humanoids , for sure . Even the Big foot , Sasquatch , Ape man , Yeti , abominable Snowman etc. are all part of this "Humanoid Saga" , that existed in bygone ages...