Hi Bailey! I think your composition on this piece is nice, I really enjoy the way the characters are framed by the nature elements around them. I think one thing that jumps out to me is that the characters have so much small detail to them, which make them feel a little out of place when compared to the environment. This is very common, and is usually a result of zooming in a lot when doing digital pieces.
My advice is to simplify the characters a little bit and include larger shapes to fit the environment. I think if you do the opposite and make the background more detailed to match them then the piece will become too busy. Really focus in on making interesting shapes! The cloud in the background is so fun and cheerful, and I’d like to see the characters match that.
Overall I love the story here! The pirates and mermaids getting along really suggests to me that two different worlds can find similarities and form friendships. It’s interesting because they’re often in stories together, but usually as enemies of some sort. Usually mermaids are seen as very feminine and pirates as very masculine, so I like to see that they can be combined and encourage the idea that they can get along.