Both of the items you mentioned have intrinsic value. Intrinsic means: Innate, inherent, inseparable from the thing itself, essential. The value of both of your objects is tightly connected to the object itself. People find these objects valuable based on what they are, not some outside authority's fiat. The value of fiat currency, however, is not intrinsic: The value is tied to the reputation of the backer, and is typically legally mandated by that backer. If that reputation goes down the drain (e.g., a nation-state collapses) or that law is repealed (e.g., "demonetization" of old currency), the fiat currency isn't worth the paper it's printed on... except, perhaps, in the distant future as "numismatic" value for collectors.
As for your distinction between "useful" objects like shoes vs. "useless" objects like a famous photograph, this is meaningless economically. Things have value simply because people want them, and are willing to trade what they have for what they want. To someone who doesn't wear shoes, those shoes of yours are equally as useless as a Trump photograph. Equally, to someone who collects photographs of celebrities, that Trump photo might be highly useful. If someone were collecting such photos and you tried to sell them a pair of shoes instead, they'd probably laugh at you and walk away.
You think one object is "useful" and another "useless." Other people's ideas of utility differ. There is no universal standard of "useful" that automatically translates into value, and that so many people think there is, and want to impose this concept onto free markets, is probably one of the biggest problems with modern economics and centrally-planned monetary policy.