The Treachery of Images by René Margritte
The text in the painting reads “Ceci n’est pas une pipe” which (more or less) translates to “This is not a pipe.” What Margritte is saying is that literally it is not a pipe, it is a painting of a pipe. But it’s also not just a painting of a pipe, it is an image of what Margritte holds as his internal concept of a pipe.
Communicating complex ideas to others is difficult because words hold different meanings for different people and the more nuanced the more language starts to get in the way. But all communication is imperfect.
It’s not solipsistic though because much of the meaning you might hold for words is contextual to the people who taught you language and your relationships with others. Your conception of those word’s meanings are your interpretation of the meaning someone else holds. Language and communication are much more effective viewed from the perspective of collaboration rather than expression. In other words working to establish shared understanding makes communication more effective.
A significant reduction in the population leads to better outcomes for the survivors. Mass death events in history, such as both world wars and the various pandemics, are usually (but not always) followed by a period of progress and prosperity.
Humans breed faster than their civilizations can keep up with and in the modern era scarcity is artificially created by arbitrary ownership of natural resources. Fewer people means more resources per person.
However if your hypothetical pandemic were to strike, it would create a problem the world has never encountered before (at least as far as I can find) so predicting what might happen is basically guess work. Given how violent brutes tend to be more successful in scarce environments, the outcome would be very grim.