This. You also want to see how coachable they are. If you tell them to adjust something on their swing or throwing, do they try to do it or do they ignore it, that sort of thing. As others have said, also look for overall athleticism rather than softball ability. But I will take a lesser athlete who seems to have a better attitude.
I coach rec, and my goals for the players are first to have fun, and second to get better. My experience is that is easier to accomplish with a group of enthusiastic, coachable girls than a group of better athletes who aren't all that interested.
You're doing it right!!
I agree 100% that attitude and effort are a huge difference-maker.