elementaryos is made for that sort of thing, its quite simple and friendly and you need to poke around it to get it to even be able to do more ‘advanced’ stuff. its among the most polished DEs ive seen design and user-experience wise.
and it is still linux so you can disable or otherwise restrict their user account from anything you don’t want them meddling with. like the settings app and stuff, try it out on a VM and you will get what i mean.
oh its based off of ubuntu lts so its solid
the internet is insufferable without it, and many people (including some IT people) seem to not even mind it. it blows my mind.