Key themes in Ari and the Very Loud Bird! are problem solving and creativity, agency, support and acceptance, and good humour.
Explicitly, this is a story about a young kiddo asking for help when they have a problem, exercising some independence, and using their own creative ideas to actively solve the problem--even after things go terribly wrong.
Implicitly, the story and illustrations show Ari's stable and supportive family. Ari is a non-binary child, and their family-stability is strongly linked to the theme of agency. Having a stable and loving family affirms that Ari is both safe and supported while they are exploring their ideas and expressing their personality.
Like Ari, young readers are learning to regulate their own big feelings. They can relate to Ari being frustrated, hollering to Dad for help, and throwing socks around the hall impatiently. Kids know what it's like to be a kid. Like Ari, they get worked up, actively develop and try out their own creative ideas, and learn as they go.
For non-binary children, or kids exploring gender identity, the theme of loving support and acceptance is affirming in this story. As a young, non-binary protagonist, Ari is a kid doing kid things. The story isn't about Ari's gender identity, which is simply identified in the book with "they/them/their" pronouns. Gender identity is accepted as a simple matter of fact in the story without putting Ari under scrutiny. For 2SLGBTQAI+ families, I hope this is simply an affirming story for those reasons.
This story also affirms the importance of showing support and acceptance, being good humoured, and trying again when things go wrong!