>>281369445I don't think it's quite that broad, though the particulars of the broad reading are sound. It's just more about how they're expressed personally. Emma's not some platonic ideal of a lower class maid, she has her own history and relationships that define her.
Emma is humble both because of the harrowing life she's led and the kindness and grace of her first patron and mistress. It's never really pointed out in the manga explicitly, but think of how shocked people are by her bearing and and education. Emma not only had a secure job with a very easy to work with lady, but received way more than a maid could ever be expected to have in terms of her learning. All this other stuff being foisted upon her now is even further beyond that, and she flinches at receiving any more because of it. Mrs. Stowner was also, from what we could see, a fairly severe but kind-hearted woman, and practically being raised by her probably left an impression too. Kelly certainly wouldn't have allowed Emma to be vain and materialistic, even as she pushed her toward William. She did so purely for Emma's emotional happiness, not because of his wealth.
Mrs. Jones and Dorothea have their own particulars too. Mrs. Jones has long bucked the conventions of her class, and her friendship to Dorothea is almost certainly in part because the latter also comes from a less rigidly ordered society. It's not so much that they're freer with Emma than they should be because they want to prove that class is irrelevant for their own egos, but because it's the kind of thing they prefer. They want this sort of thing to be more common and more accepted, and are well aware that it isn't. I forget the particulars, but I'm certain the way this blows up ends up highlighting that they were a little thoughtless in doing this.