In any case, the condemned man looked so like a submissive dog that one might have thought he could be left to run free on the surrounding hills and would only need to be whistled for when the execution was due to begin. (1)
Our very first description of the condemned man makes him out to be both a wild animal (he'd run loose) and a submissive animal (he'd come back on a whistle). Very little in his initial description makes him seem like a human being.
Instead of getting up and begging pardon, the [condemned] man caught hold of his master's legs, shook him, and cried: "Throw that whip away or I'll eat you alive." (13)
The only time we hear the condemned man speak in the book, and he threatens to eat somebody. It's hard to tell in this case whether he's speaking figuratively or literally. Given how he otherwise appears, it's not that hard to believe he is actually threatening to eat someone. This makes it clear both that the condemned man is actually a very aggressive and probably violent person, and that the penal colony itself is a brutal and beastly place. One wonders if lots of the people there are like animals and whether people like this need an extreme justice system.
When he put on the shirt and trousers both he and the soldier could not help guffawing, for the garments were of course slit up behind. Perhaps the condemned man felt it incumbent on him to amuse the soldier, he turned around and around in his slashed garments before the soldier, who squatted on the ground beating his knees with mirth. All the same, they presently controlled their mirth out of respect for the gentlemen. (39)
That the condemned man and the soldier play and joke together might strike you as remarkable, since only a little while ago the soldier had strapped the condemned man into an execution device. Apparently they don't feel themselves to be opposed. Perhaps they're brought together by a sense of brotherhood against the superiors or "Law" they must obey? Here, they clearly see themselves as distinct, in their lowliness, from "the gentlemen." This moment of play could be a human moment in the midst of a nightmare, but Kafka's language – "guffawing," "squatting on the ground beating his knees" – instead casts it in a rather grotesque light. Here both the condemned man and the soldier seem slightly subhuman, more like brutes or animals.
So this was revenge. Although he himself had not suffered to the end, he was to be revenged to the end. A broad, silent grin now appeared on his face and stayed there all the rest of the time. (43)
We leave it up to you to decide whether the condemned man's obvious and rather sadistic desire for seeing the officer suffer makes him more human. Is revenge a uniquely human desire? Or does it instead just bring out all the more his beastliness and brutality?
This phenomenon made the condemned man completely forget the explorer's command, the cogwheels fascinated him, he was always trying to catch one and at the same time urging the soldier to help but always drew back his hand in alarm, for another wheel always came hopping along which, at least on its first advance, scared him off. (45)
This is a grimly comic moment in the midst of catastrophe. The apparatus is going to pieces, the officer is being cut to pieces, and the condemned man is off playing with the cogwheels as they fall out of the dying machine. Like a baby, or an animal. Also like a baby or an animal, he's scared off each time a new wheel comes at him, as if he's surprised by it and doesn't get what's going on.