One of the sections of the ending that strikes me forcibly is the final paragraph of the story. The existential significance of this tale is shown by the way in which the life of Gregor is so quickly forgotten and the ease with which his family, and especially his sister, who had once so loved him, move on and completely forget about him and the past. Note how this is referred to at the end as the family members meet and discuss their future and their options:
As they were conversing, both Mr. and Mrs. Samsa, upon seeing the daughter becoming more and more vivacious, realised almost in unison that lately, despite all the sorrows that had left her cheeks pale, she had blossomed into a lovely and shapely girl.
Note the euphemistic allusion to everything that they had endured as "sorrows" only. No mention is made of Gregor. They are only thinking about the future, and this is a future in which Gregor has no place. Human attachments and bonds of love are shown to be completely transient and almost illusory through the ease in which the Samsa family moves on and forgets Gregor.