If you still think Windows is a good OS today, then I don't know what to tell you. Microsoft realized about when Windows 10 came around that Desktop os/software isn't the future and is now trying to milk that cow for as long and hard as possible while putting the minimal amount of effort into further development. Just enough to still be more attractive to the masses than MacOS or Linux. But with everything moving to the cloud, they'll eventually run out of breath if there won't be something leading to a reversal of that trend.

And honestly, if you want your kid to tinker and break things and be able to look under the hood, isn't Linux the perfect choice anyways? At least if they have some interest in the technical aspects and don't just want a gaming rig.