Maureen O’Sullivan was lucky that Cheetah did not tear her apart when she was making the Tarzan movies. She later wrote that Cheetah was jealous of her. Cheetah was gay and had a crush a Johnny Weismuller. I think she got bit.
All the chimps they used in the Tarzan movies were females and, as with most films that use live animals, a number of lookalikes were available to film depending on the behavior they needed for each scene. Nobody with any sense would work with a male. They are about as large as a smallish human and incredibly strong and aggressive.