Unable to change my Home Screen wallpaper on iOS 18.2 in iPhone

I want to change my homescreen wallpaper on ios 18.2, and it’s not working very well.

My homescreen picture has a picture of a pet who I recently lost, but I can’t delete it. Why not?

Yes, I can create a new wallpaper, but both Lock Screen and home screen are always the same. There doesn’t seem to be an option to use different pictures. We seem to have lost a function here.

Yes, I can select pictures from my Photos collection, and I can even select from albums, but it’s not showing the album that does actually exist and has the photos I want. Seems to be a bug. I can’t find them in the thousands of pictures I have in Photos without an almbum search that works.

[Re-Titled by Moderator]