If you're competent enough to use Lemmy, you're absolutely competent enough to run Linux for most purposes.

Honestly, it's a bit more of a stretch, but if you're competent enough to plug in a USB drive you're probably competent enough to install Linux. And most of Lemmy would be here to help you!

My sweet, darling, luddite of a partner struggles with changing the ringtone on his phone, but didn't run into problems using linux.

You're fine.

This video has a lot of self-hosting and somewhat advanced stuff being mentioned, but if all you want to do is start dipping your toe into Linux then it's not nearly as hard as you'd think. I would try running Linux in a VM (i.e. VirtualBox) to get a feel for how it operates and build up confidence that way, as well as maybe watching some videos on how people set up and use their Linux etc. It will be a learning curve, but as long as you pick a beginner-friendly distro (e.g. Linux Mint) it's really no more difficult than if you started using Windows for the first time. Keep backups of your data and/or put Linux on a secondary computer and you should weather the initial few weeks just fine.

On the upside, when you have problems in Linux there will be logical solutions with answers that can be searched for, whereas in an OS like Windows or Mac the solution is probably "I dunno! Reinstall?" or "You just can't do that, sorry". It's also understandable if you don't want to touch anything complicated, but I do think one of the best parts of Linux is really just getting messy, making mistakes, and learning. Because things in Linux make sense, over time you'll learn how to use a computer again. I feel strongly that Windows/Mac/Android/iPhones have (intentionally) dulled the average person's computing skills and put them into a state of learned helplessness. Everyone thinks computers are complicated wizardry because nothing on those proprietary operating systems makes logical sense, and trying to troubleshoot anything results in wasted time and frustration.

A good thing about tech is that if you have a spare device (even a cheap single-board computer like a Raspberry Pi or similar cheaper one, or a partly-broken laptop) or a working virtual machine, you can break things. That's a core characteristic of the old-school hacker mindset, to try stuff and break stuff until you understand stuff. Usually, the worst case, you just reinstall the operating system and have a fresh clean environment (or, better yet, you restore a backup you made! Learning how to fail gracefully is a great skill)

I bricked a certain wacky laptop setup twice and had to start over (luckily with backups) just trying to get a custom startup loading screen. But once I realized why it was breaking and how to avoid it, I had a cooler looking computer!

Tech is made to make us feel stupid, so you are not alone in feeling that.