I was in a very similar situation a few months ago, still there but there have been some improvements, and it's tough. I think so many things can create this atmosphere in a group of kids- lack of previous success, the environment of the gym, prior coaching styles, unsure what to do with someone new/different, following cues from teammates, and sometimes they really just flat out don't want to be there. And none of those things can be fixed quickly, and some cannot be fixed at all. Keep working to earn their trust- tell them that you see potential in them, it's possible they haven't heard that before and are working on the assumption that they just aren't that good and don't see a point in working hard.
My tactic was to really focus in on the kids who did show at least some degree of respect and receptivity to what I was doing, no matter how small, and earn their trust. That's not to say I ignored the other kids, but I tried not to let them get the best of me when my corrections went ignored or they continued to act disrespectfully. Instead I focused on the successes of those who were trying, even if only a little, and hoped that their success and progress would be enough to win over some of the other girls. Sometimes it only takes one to buy in and see that you really do want what's best for them and only trying to help make them better to convince others to buy in as well. But it took a lot of time, and I'm still not there.
You're in a tough place, and you probably won't win them all over, but aim for the small successes. Best wishes!