Tarzan has been dusted off, his abs polished and his vocabulary spruced up in David Yates’ handsome but altogether pointless “The Legend of Tarzan,” a chest-thumping resurrection of the Ape Man that fails to find any reason for the iconic character’s continued evolution. On the one hand, it’s easy to see why Tarzan has yet again swung back into our lives: Tarzan and Hollywood were born almost simultaneously, like conjoined twins of a new pop-culture machine.