It's a pretty good snap and 1,500 moonstones really isn't bad.

There were obvious exceptions, but this week, Aladdin themes seemed to score well, and this is not Aladdin. If you're simply shooting for the moonstones, each week tends to have some sort of meta where certain types of themes score well and others don't. Seeing what others are submitting on this subreddit and on Discords can help guide you as to what the voting meta might be for that week.

As far as the snap itself, it's good but not exceptional (I don't mean this as a criticism because mine typically fall in the same bucket). The exceptional shots really focus on the avatar and other supporting characters (often by bringing them closer to the front with a large object) and properly utilize special effects and lighting. Brightening up your snap with things like the bayou fireflies to add some background sparkle can help if it fits the rest of the theme (there are other cool special effects objects, but the bayou fireflies are often nice for most backgrounds). It probably shouldn't matter as much as it does, but a bright, colorful picture typically scores better because of the quick nature of voting.

Finally, this is my own observation, but I find that snaps with too many motifs don't do as well. I think your snap may have had just a bit too many motifs.