Frankenstein's monster is a shambling moron; Conan is a mighty-thewed violent barbarian in a loincloth; and Tarzan is an ape-man whose great intellectual accomplishment is "Me Tarzan, you Jane."
The Creature is a brilliant and eloquent autodidact; I'm told Conan is a mighty-thewed barbarian who wears as much armor as he can get, is fairly smart and cunning, and becomes something of an intellectual as King of Aquilonia in his later life; and Tarzan teaches himself to read and write English solely from books (bootstrapping from children's primers and an illustrated dictionary) despite having no human spoken language at the time, his first one of which will be French, learned as an adult. He also becomes an intellectual omnivore when finally dragged off to civilization.
On the flip side, I'm not sure people remember Sherlock Holmes's physical side: he was quite athletic and a master of I think jiu-jitsu.
Seems as if up into the early 1900s heroes (or even interesting villains) were accepted or even expected to be well-rounded if not superhuman in both brains and brawn, but after that separation occurred, with rare exceptions like Khan Noonian Singh -- but his very well-roundedness is a threat, that of "eugenics". Or Batman, but he both has old roots and isn't that strong in a superhero context. Or Adrian Veidt, but he's a deliberate throwback.
If you're wondering what brought this on, the answer is that I followed A Princess of Mars with Tarzan of the Apes by the same author.
See the DW comments at http://mindstalk.dreamwidth.org/400653.html#comments