@randomperson42 First of all, welcome to the world of photography and
Talk Photography forum.
Okay...
Normally the first important thing to think about is the camera body, not the lens. You need to find the right kind of camera for your needs, but the most important thing is you need to feel right with the camera. You need to know if you feel comfortable holding it, and taking photos with it. No point in buying a big camera if you got little hands, no point in buying a small camera if you got big hands. You also need to fee comfortable being able to reach for any of the controls as well as the weight of the camera.
Once you're done with the camera body and after you've bought the camera body, then the next thing is yes, the lenses are the important parts. Yes, Google could be right about the lenses being more important than the camera body. That is because you would need the right sort of lens for the right kind of photography. Although anyone new to photography would assume it is a case of no point buying a wide angle lens for a football match, or a 1000mm lens just for taking a landscape photo. It really does deeper than that. There's the questions of which lens can let you take photos in much lower light levels, which wide angle lens is better before it starts showing distortions in the photos, and so on.
But usually for many photographers, the body is the important thing to start with first and just get whatever lens you can get to go with it. You need to take some time familiar yourself with the camera, improve your skills with the camera, light levels, exposure settings, and all that. As we gain experience, we tend to start being careful with the choice of lens.
You can get the camera body and the lens separately. But usually a kit (a camera and a lens) is cheaper than buying them separately.
A budget of £200 is only good for second hand cameras that were made about 10 years ago. A Nikon D200 could be bought for around £200 depending on where you can find it. But the D200 were made roughly 10 years ago, nowadays it's a D700. I don't know much about Canon, so I would guess it's something like buying a second hand 300D when nowadays they have brand new 800D.
It would be kind of like with limited budget, you can only buy a second hand Apple iPhone 4 when nowadays most would be buying iPhone X or 11.
But the good thing is that as long as you stick with the same brand camera, you can in future upgrade your body but keep the lenses.
As for trying to take photos so you could use them as a desktop background. The trouble is that it boils down to the different ratio between a photo and a screen. Many of the cameras are roughly around 4:3, that's like the shape of a television, monitor, paper, etc., but nowadays most desktop computers have widescreen monitors. If you try to use a photo you took with a camera as a desktop background, either you crop off the top and bottom parts to fit it in, or fit it in between the top and bottom but leave black bars at both sizes, or squeeze it in. But if your monitor is not one of those widescreen types, then you'll do fine.
If you got a widescreen monitor, then when taking photos with a DSLR, you have to use your eye to frame the subject. You may be looking at the subject in a 4:3 viewfinder, so you may need to image an imagery widescreen, and try to frame the subject within your imagery widescreen. Most camera models can have the option to turn on a grid setting, where you'll see lines in the viewfinder, sort of shaped like a hashtag, so you could use those lines to get a rough idea of how to frame the subject for a widescreen monitor to use as a background desktop.
Well, when you start, you need to accept that your photos won't be that good, you'll be lucky enough to get the one you hope for. You just need to know that it would take you time, a matter of weeks or months, depending on how often you take photos, to build up experience to get the right look for your monitor as a desktop wallpaper. Good thing is that with a memory card, you can just keep trying by trial and error, don't worry about having some bad photos. In the old days of film, we can't afford to waste rolls of films trying to get the right photo, so we tend to have to try to get it right as best as we could.
Anyway, hope this all helps?