I devoured ERB's books as a teen back in the seventies. Read pretty much all of his SF-flavored books, including the Caprona trilogy, The Moon Maid, The Monster Men, etc. And read my fair share of the Tarzan novels as well, starting with a couple of battered old hardcovers I found in my grandfather's attic.
But, in all honestly, I discovered those books after watching the old Johnny Weissmuller movies on TV, and the new color movies at the drive-in. Can't remember a time when I wasn't used to the idea of multiple different actors playing Tarzan. Throw in the original novels and the Gold Key comics and the Big Little Book, and, yeah, Tarzan always came in different flavors.
Just like James T. Kirk these days.