It seems completely remarkable that a person would wake up alone in the forest, having been beaten and tied up with ropes, and not feel remotely angry about his situation. However, this is just what happens to the bound man of this story. He lies on the ground for quite a while, testing his bonds, seeing how much movement they afford him, and he even seems a bit amused to find himself thus. The narrator says,

He showed no sign of fear or hurry, though he thought he was unable to move, until he discovered that the rope allowed his legs some free play, and that round his body it was almost loose. His arms were tied to each other but not to his body, and had some free play too. This made him smile, and it occurred to him that perhaps children had been playing a practical joke on him.

It is hard to imagine doing the same thing in his situation, but rather than fight against his confines, the bound man tries to simply learn how to work within them. He begins to find it somewhat fun to do so (after one or two flops on his face). The man even attempts to avoid stepping on flowers, despite his own terrible condition—he is injured and bleeding, and bound to boot.

The rope was knotted at his ankles, and ran round his legs in a kind of playful pattern . . . To avoid treading on the thistles with his bare feet, he hopped over them like a bird.

It's a strange word choice given the man's circumstances—"playful"—as though he's only been tied up as a joke and not as a way to injure and rob him. However, he learns to walk and jump by paying attention to his bonds and accepting their presence rather than fighting them. This appears to symbolize those limitations that human beings all have as a result of our finite and mortal nature. We can fight them or we can learn to work within them, as he does. This is likely one reason the character is not named, because he actually represents us all. The narrator says,

In that he remained entirely within the limits set by his rope he was free of it, it did not confine him, but gave him wings and endowed his leaps and jumps with purpose; just as the flights of birds of passage have purpose when they take wing in the warmth of the summer and hesitantly make small circles in the sky.

Here, the bound man is compared to birds, and birds are often associated with an almost supreme freedom as a result of their ability to take flight. This simile emphasizes the feeling of freedom the bound man ironically experiences. He shows that it is possible to make the most of our limited human condition and to achieve great things, even while we remain limited. He does not perceive of himself as bound, as he's learned to navigate his bonds, and so he feels free.