I think Doyle purposely exaggerated Challenger and diminished Malone, in order, to show how they changed when they returned from the Lost World. Challenger's wife is so correct when she yells at him for being his own worst enemy. Malone will turn out to have more confidence and also see Gladys as she is.
Doyle's description of Challenger is some of his best writing. The man is a caricature, a bull like human, mythological in the size of his head and his raging temper. One wonders if he is part Minotaur. He is not the only caricature here, for his whole household is made of exaggerated residents. There is the snide Butler of few words who, in Jeeves and Wooster fashion, makes sure to open the door so his master and Malone can tumble out onto the street, and there is the exotic Mrs. Challenger, the beauty who tames the beast, the beast being her professor husband. As ridiculous as these characters are they do have a certain charm about them, and they are likeable much like the characters in a Fleischer Popeye cartoon. Come to think of it, Challenger does come across much like Bluto...
Derrick I didn't think of mythology, but I think you are 'spot on.'
I thought it was interesting here that the idea of pretending to believe others was introduced, which seems quite complimentary to the subterfuge nearly every character is thus far engaged in. In Challenger we at last seem to have a redeeming, if flawed, character. If the story can be believed Challenger is the only person adhering to the truth, and he instantly calls out Malone for being the "damnedest impostor in London." He is breaking the rules of the story practically as soon as they are set.
A weekly discussion group of Sir Arthur Conan Doyle's "The Lost World"