Art may be useful (or at least usable and realistic), e.g. imagine providing instructions how to get the photo from that camera for (hopefully) people in 1000 y

Art may be useful (or at least usable and realistic), e.g. imagine providing instructions how to get the photo from that camera for (hopefully) people in 1000 years, or even describe what that cilinder on a pole is in the first place. Science experiments demonstrating discoveries of the past centuries (magnetism, electricity, radio) are a kind long-term useful art.