I think Debian would be fine for that unless you’re expecting the kid to install, set up, and administrate the system. Would be a good learning opportunity for a teenager though

…consider the question, what is Debian for?

It’s primarily a server OS. Not every distro needs to be good-to-go for desktop/workstation/gaming/mobile use cases out of the box in order for them to be “easy”. This is a big part of why there are a huge basket of distros to choose from, many are for different focuses or specific purposes.

And I didn’t say Debian is only a server OS…

Debian is Debian made easy