Apes and blonds are an oddity of plot dynamics in horror movies in the 1940s through 1960s. I have no expert opinion to give as to why: just accept it. Hillbillys in a Haunted House (1967) also has John Carradine, Basil Rathbone, Lon Chaney Jr., and music. Let the mirth begin. This is one of those movies you just itch like crazy to see. I have no explanation for that, either.