That's a great question! In addition to what others have mentioned, if you're unable to find an explicit "internship" or volunteer opportunity for your age group, what you can do is find other ways to continue learning and broadening your experience. Then, when you're looking for internships next year, you can show how you problem-solved and were able to continue growing during this time: "Companies weren't taking on people my age, but I did the following to continue learning and grow my experience:......"
I don't know what is feasible for you, but there are a few options you could consider, in addition to the ideas already mentioned:
- Contact folks at companies you're interested in and see if you can shadow one or more of their employees. You could do this for a bunch of companies and get a wide range of exposure to different workplaces! If you go this route, I would suggest waiting a bit closer to the summer to contact companies.
- Spend some time working on a self-created project. It doesn't have to be a "startup," per say... But you could do work on background research (e.g., explore different market opportunities or customer needs) and lay out the groundwork for a company/initiative you'd be interested in building some day. You could even go out and start a project or make an app for your community! Times like this are great for entrepreneurial spirit.
Again, these are all just ideas. What you get to tap into is "What am I really interested in learning and developing?" and then you can find a way to go do that without the pressure of a specific internship.