high school Jim was a hero....He seemed to move in a continual spotlight...He seemed always at the point of defeating the law of gravity...

Jim was the high school all-American hero, who ran out of steam and never achieved anything particularly noteworthy after his glory days. He is completely ordinary. However, he retains his good nature. He teasingly calls Tom Shakespeare in reference to the poems that Tom writes. He is friendly and outgoing. He is described as “heartily” extending his hand to shake Laura’s when Tom introduces them.

Jim leads an ordinary existence, but he has aspirations. He tells Tom that he attends lectures on public speaking and wants Tom to attend too so that they can improve their opportunities. He hopes to achieve “social poise” to move out of the warehouse and become management:

Jim: You and me, we're not the warehouse type.
Tom: Thanks - that's good news. But what has public speaking got to do with it?
Jim: It fits you for - executive positions!

Jim’s friendliness—which Amanda contrasts with Tom, saying, “I don't know why my son is so stand-offish - that's not Southern behavior!”— serves to bring Laura out and also to show their differences. Jim is not happy with his current lot in life, but he is not living in a dream world as Laura is. He is not staying home and watching the parades go by.

He is actively living his life and, at the same time, making real efforts to move forward. He has an ordinary job but is attending lectures to improve his chances. By contrast, Laura just wandered the city during the hours when she was supposed to be in business class. She lives in a dream world, or inside her own glass menagerie.

Jim hopes to fulfill his dreams, but remains solidly in the real world. Tom’s remarks at the play's introduction underscore how the Wingfield women live blindly without seeing or being in the real world in contrast to Jim. Tom says,

the huge middle class of America was matriculating in a school for the blind. Their eyes had failed them or they had failed their eyes…

Jim might be deluding himself about "social poise." It is not clear whether the playwright intends the audience to scoff at Jim's ambition or not. Nevertheless, Jim is solidly part of the world and hopeful, not apart like Laura.

In a play that concerns characters who are often embroiled in their own illusions and fantasies while carrying out a remarkably dysfunctional existence, Jim serves as something of an ambassador from the normal world outside of the strange bubble in which the Wingfield family lives. Tom's descriptions of him imply that he is a completely average and ordinary man, and Jim's actions and demeanor do absolutely nothing to contradict this. In fact, Tom sometimes seems frustrated that Jim could never hope to understand Tom's dreams of adventure and a novel existence.

In many ways, Jim is only significant in how he affects Laura. Trapped in a world of her own imagination and strongly disconnected from reality, Laura seems to almost worship this utterly average man. Jim's entire purpose in the story is to serve as the unwitting catalyst that forces Laura to face reality. Though he treats her warmly and with kindness, he shatters her favorite glass unicorn and reveals that he was engaged all along. This is only significant to Laura, who looks at this self-proclaimed klutz as more of a knight in shining armor. Laura's realization of this illusion is what forces her to face the real world.

In The Glass Menagerie, Jim O’Connor is Tom Wingfield’s friend from work. To satisfy his mother’s nagging, Tom has invited Jim to dinner at their home. Jim is the antithesis of the entire Wingfield family. He is firmly grounded in reality, has realistic expectations and ambitions, and is not a dreamer. In Amanda’s mind, Jim is the equivalent of the young men who clustered around her in her youth: a “gentleman caller.” Laura remembered him from high school, where he was popular and successful, while she was ill and often absent. Jim is at ease in most situations and, as he can tell that Laura is a nervous person, tries to put her at ease as well. He treats her kindly and warmly, but he also provides the instrument for making her face reality when he accidentally breaks the unicorn. Jim lets her know the truth, that he is engaged. Her gift of the broken unicorn can be interpreted as Tennessee Williams’ way of highlighting the young man’s ordinariness; like the horn-less animal, he is just like everyone else.