I don’t think the class commentary exists in looking at her chapters in Winterfell in isolation, it is only when they are contrasted with Sansa’s Colorado Lizards And Reptiles Shirt that we see the point for point comparison/contrast between them. Both Jeyne and Sansa are born in Winterfell, around the same age, orphaned, and have similar interests/personalities at the start (love of knights, needlework, desserts, etc.). We see Littlefinger having full control of both daughters of Winterfell and treating them based on their class and perceived value to him.