A character analysis is something that breaks down and evaluates the specific traits of a literary character. This will include discussing what the character looks like, but a strong character analysis will also analyze personality traits, motivations, relationships with other characters, and possibly look at how the character influences themes and/or conflicts within the story.
Sammy is the story's protagonist. He is a 19-year-old youth working at a small town grocery store. Additionally, Sammy is the story's narrator, so that should immediately alert you to the fact that everything being told to the reader is being looked at from and through Sammy's worldview. This colors Sammy's opinion of the people around him, and in general, Sammy does not think highly of the people that he has been hired to help in the store. He repeatedly refers to them as "sheep" or other dumb barnyard animals. This shows readers that Sammy not only has a low opinion of other people, but he has a fairly high opinion of himself. We see this in later parts of the story as he believes he could be welcomed into Queenie's house or rewarded by the girls for his "heroic" actions at the end of the story.
Despite Sammy's seemingly negative attitude about the people around him, readers do see that Sammy has a sense of justice about him. He believes that Lengel is acting unfairly toward the girls, and Sammy decides that he needs to take action to either save the girls or show support of their actions. His decision doesn't end up working as intended for him, but that doesn't change the fact that Sammy took action to help someone he felt was in need. That's a seemingly honorable trait of Sammy's; however, a reader should question Sammy's initial motivation. He isn't helping the girls out of a sense of altruism. Queenie is very attractive, and Sammy is hoping that his actions result in some kind of relationship. There is a sexual motivation in Sammy.
The motivation could be more than sexual as well. Sammy might be motivated to impress Queenie in order to obtain upward social status. He is clearly a blue collar worker, and Queenie is portrayed as a member of the wealthy class based on how she acts, how she dresses, and what she buys. Queenie is Sammy's chance to move up in the world, and that again shows that Sammy is selfishly motivated for personal gain.