The issue of "originality" raised its head as soon as photography evolved beyond the daguerreotype (which could not be reproduced). As soon as you had a negative from which a print could be produced, you can theoretically produce infinite indistinguishable prints.
Photographs exist as art basically because the photographer or their agent promise to only produce a limited number of prints from an original.
I do some hobby film and digital photography, and it's been my experience that people love getting prints of the photos I've taken of them on film. Digital photos can also be printed, of course, but there's something (not clear what) special about knowing that a physical process other than an inkjet printer produced the image.
Photographs exist as art basically because the photographer or their agent promise to only produce a limited number of prints from an original.