As with many people, my first jobs as a teen, some years ago, were in retail/food. And based on the experiences I had, I can tell you - you're overthinking this. People hiring for entry level positions in those fields are generally looking for someone who will reliably show up on time, follow simple directions, and not goof off or do horrible things while on the clock. The list of qualifications isn't extensive or deep.
That said, there's no reason to miss this as an opportunity to start honing your resume, and to work on learning how the job market behaves.
One good technique, which will help answer your questions, is to use research to understand how to format your resume for a specific position. For instance, if you're interested in retail, find as many retail job postings as you can, and write down the trends you see in the job descriptions. Then, as you write your resume, frame your own experience/skills from the perspective of those trends. You don't want to sound too generic, and you certainly don't want to falsify anything, but this technique can give you a good frame of reference.
For instance, if interacting with customers is a common duty for the positions you're looking at, when you're writing the section of your resume that describes your art commission business, you can be sure to call out customer interaction skills:
Responsible for working directly with customers to understand their needs
The key to this approach is using the job posting as a research tool to understand what part of your own experiences you should emphasize, and what language to use when doing so.
You can also do research via other channels, such as company websites or other media channels which may describe the culture, mission, or other guiding factors at that workplace. Maybe you're applying for a retail position with a local company that prides themselves on being family-owned - you can describe some aspect of your work or skills that shows how that fits with your background, too - or whatever other aspect matches what you're learning about your target employer.