I believe you are correct, the product key is the important part. I can't imagine the USB containing anything special, and I've used the media creation tool multiple times without issue.
I doubt that little bit of thickness would have any effect on the sensor, but I think you would be the best judge of that. If you don't notice any difference, I think all is well.
$40? Damn, they really hike that price up in Canada don't they?
What about Terraria? Also, Risk of Rain 2 apparently runs on a potato. And of course, there's always Minecraft
Assuming this is just for light programs such as Word and the like, AMD makes Ryzen APUs for cheap. I'd recommend a 3200G or 3400G, and a B-series chipset for a good budget office build.
It could be that the components (namely the capacitors) just needed to discharge. There's a reason people always ask if you've tried turning it off and on again, and this is a prime example.
Also, welcome to the forums!
Make sure you have a speaker installed, it should look like a small black cylinder on the motherboard. If you don't have one, I'd recommend getting one