it's all certainly interesting because it's so obvious from the start that Lapis has gone through some traumatic event in her childhood that makes her view commoners with as much derision as she does. Especially when she's shown to be fully capable of seeing Natori a commoner from another world as a perfectly capable person who can be just as skilled and classy as nobles are. But somehow there is a mental block here that stops her from connecting those dots that makes her view the commoners of her world as barbaric nonetheless.
Don't see how those contradict. She doesn't view the peasantry as intrinisically inferior, she says herself that they are "barbaric, selfish and easily angered" due to their lack of education. She just doesn't have any reason to give a damn about their welfare, especially considering there is anti-noble unrest among the common folk. She quite clearly makes a distinction between the unwashed masses and specialist craftsmen, such as the ones making magic jewelry.