WD is something you get with Windows OS and should not be considered premium protection, so even though some will tell you that all AVs are equal (useless), that is simply not true. I don't want to advertise any such product, so I leave it to anyone who wants to know more and knows how to use search engines.
If you want to change something about the problem you are constantly running into, you have to change the way you use your computer and the internet, otherwise no antivirus or operating system will protect you.
I know that Windows defender sucks. At times, I would even use scripts to disable windows defender and auto update. But with time, I realized that, we need at least windows defender, even if it sucks at it's job. You know? Like a basic defense. It's better then having nothing. Someone might say, why not just use other third party antivirus? My device is old, I try to install as minimal as possible to keep the load minimal. For me, it felt, heavy when using an antivirus. Background running services makes it more worse. That's why.
I would say the easiest out of those open source operating systems is going to be a Linux based distro that would have a good user interface and themes which will help windows users to easily get used to it. Linux distro like Linix Mint is going to be my choice if someone wants to have a safe operating system that looks similar to Windows.
I tried to shift to Linux (Mint METE latest). But eventually reverted back to Windows as I found some difficulties. There will always some things that you'll miss when using Linux. Most of us are used to Windows. Anyway, I'll try to install Linux again. to make myself more comfortable.
Another free and open-source operating system that I used in past which's very similar to Windows XP is ReactOS.
Thank you for the suggestion. I'll check if it's still running or discontinued and then decide.