All Photos on iPhone should be all photos.
Why is it that when I save a photo sent to me in a text that I can't find it in All Photos? Why is that photo in "Recents"? Why does "Recents" contain 10046 photos? Recent should be recent, lets say 6 months but not 7 years. Because that is how long it took to get that many photos.
All Photos should be just that, every last photo that is in photos should be in there. If you didn't save it to photos is the only excuse.
Someone who programs this need to see why the program is not making sense.
iPhone 6s Plus, iOS 13