The meaning and the significance of The Ballad of the Sad Cafe

So in Carson McCullers's "The Ballad of the Sad Cafe" a fellow, generally described is simply The Hunchback but addressed as Cousin Lyman, shows up unannounced and unknown in the small Georgia town and becomes the central figure in the story. Let's look at Lyman for a moment: he's first seen approaching the town on a long, empty dusky road, arrives looking very bedraggled, small and of indeterminate age (later he claims to have no idea how long he's been on the earth, 10 years or 100 years); Miss Amelia pats him on his hump and invites him in, and, to everyone's surprise, he takes up residence in her house - though nobody's sure of the nature of their sexual relationship, if any. She feeds him well and rubs him with various lotions to build his strength. Then, after several years, her ex-husband, Macy, gets out of the pen and returns to town; Lyman, immediately taken with Macy, follows him around, tagging after him, Macy being largely indifferent. Lyman desperately tries to get Macy's attention, particularly by doing a trick that always seems to work: wiggling his ears! Macy and Amelia, at climax of story, have a big free-form fight in the cafe; Amelia finally has Macy down for the count when: Lyman leaps twelve feet in the air, lands on her back, and Macy is freed and wins the fight. Lyman and Macy make a wreck of the cafe and then leave town, never to be seen again. What to make of this? Does it strike you that every single element of Lyman's behavior is exactly like that of a dog (if you substitute tail wiggling for ear wiggling)? McCullers could have made him a stray dog and it would have been the same story, exactly. Except he's not a dog - so is it about a sexual rivalry, or a sexual question that Amelia must answer, which man is she attracted to: the brute or the wimp? Or, were Lyman and Macy in cahoots in prison, and they'd cooked up this whole scheme to get vengeance on Amelia (a little echo of Playboy of the Western World)? A strange story - perhaps over-rated when put on lists of great novellas because too much left unsaid and undeveloped, but for establishment of atmosphere and for the grotesquerie of character it's quite notable.