I think you’re referring to what’s called the Home Screen—not “pages with the icons”, although that did get me there after rereading it a few times.
If so, you are able to change the home screen without changing the lock screen. Tap and hold your Lock Screen, click “Customize” under your wallpaper, click on the home screen, set it to whatever you want, and click “Done.”
If this isn’t what you see, let me know and I’ll see what I can do :)
By the way, if any of your wallpapers change to black, that usually means the photo you used for it is gone. You can keep a copy of your wallpapers out of Photos by saving them in Files as well. I know this may not help you right now, just wanted to put this out there.