Two Olympic gold medalists auditioned: 23-year old Buster Crabbe and 27 year old Johnny Weissmuller. Weissmuller won, and starred in Tarzan the Ape Man (1932), one of the top box office draws of the year.
Apparently being muscular and bulgeworthy was not a consideration.
And Tarzan the Fearless (1933), which sank like a stone and was quickly forgotten.
Johnny continued his juggernaut in Tarzan and his Mate (1934), Tarzan Escapes (1936), and Tarzan Finds a Son! (1939), 12 movies in all, becoming the iconic Tarzan for generations of moviegoers, finally retiring to become Jungle Jim in 1948. Watch his Cannibal Attack (1954) for some major gay subtexts.
He doesn't have a lot of gay rumors, though some people suggested that when his movie son, Johnny Sheffield, grew up, they became an item.
Buster had a much more versatile career, playing many action heroes, including Flash Gordon and Buck Rogers, and many Western heroes, including Billy the Kid and Captain Gallant of the Foreign Legion (1955-57). He even played another Tarzan clone at the age of 44, Thunda, in the movie serial King of the Congo (1952).
He has more gay rumors than Johnny. In Full Service, the tell-all memoir of a Hollywood hustler, he's listed as one of Scotty Bowers' clients.
Close friends in real life, Buster and Johnny competed for a girl in the non-jungle drama Swamp Fire (1946), set in the Louisiana bayou.