Yes, the photographer did not contribute more than having a camera and maybe not deleting the picture. But that's why I have chosen a meteorite as an example above: it is entirely random, the new "owner" did nothing to get it, yet we consider it his property because he found it first. I would treat the photo the same.
Copyright expressly disregards found things. As do patents. As does all IP law, because it's got shit to do with "ownership" and everything to do with activities that the government decides are worth encouraging by granting a temporary monopoly over producing duplicates of the original. The government of all modern nations have been quite clear that the purpose of that monopoly, in regards to copyright, is to encourage the
creation of new works. If you didn't author the work (or reimburse the creator in some way in exchange or incentive them to create through hire and claim the right via contract), you don't get to claim copyright.
If you steal the photo of the monkey, like if you literally stole this guy's camera with the photo on it, you would
not be violating copyright, because copyright has nothing to do with physical ownership over a thing, or even ownership over an idea, and is solely about the limited right to reproduce (hence the word COPY-RIGHT). The courts have been pretty consistent here - there are laws that govern ownership of found objects, but those laws cannot grant you
copyright (or any sort of intellectual property claim) over those objects.
That's just doesn't hold up as a defining criteria for ownership. Plenty of things are either machine-created, or happen by chance, or are unexpected outcomes of other processes, etc, and we still recognize creator's rights for their owners.
Copyright law serves a purpose - to encourage creation. This purpose is not served by, and copyright is not granted over, things that happen "accidentally" (except in the case of
intentional accidents), not does it cover acts of nature. What examples, exactly, are you thinking of where we actually give creator's rights over things that occur without any input or setup from the creator?
Also, it's important to remember that one cannot legally own the "concept of the picture" or whatever you seem to believe, only a series of rights regarding reproduction and limiting others from engaging in reproduction (which can be traded away in whole or in part, and shared with multiple other people who can do the same).