When Gregor hears his sister playing the violin, he becomes transfixed and remarks that she is "playing so beautifully." He also wonders whether he can really be "an animal if music [can] captivate him so."
In contrast, Gregor's father pays no attention at all to the music and instead fusses over the three gentlemen visitors, who seem utterly unimpressed by the music. The three gentlemen in fact seem "disappointed" and resentful that "their peace [should be] disturbed." Met with such indifference, Gregor's sister reacts with "despair." She "let[s] her hands drop and [the] violin and bow hang limply" from her hands. Her father shows no compassion here for his daughter, but Gregor does. In this instance then, given that being humane in part means being compassionate, we can say that Gregor certainly behaves more humanely than his father.
Toward the end of the story, when Gregor is dying, he thinks of his family "with emotion and love." The implication is that he understands and forgives their treatment of him. Thinking of his family in this way, especially when he is so close to a death which his family have arguably precipitated, suggests that Gregor is at this moment kind, empathetic, and thus humane. When his parents discover Gregor's dead body, however, their reaction is anything but kind and empathetic. Indeed, Gregor's father proclaims, "let's give thanks to God for that." This seems like an especially inhumane reaction from a father upon his son's death, and this inhumane reaction is of course emphasized when contrasted to the "love" that Gregor felt for his family in his dying moments.