Virtually every story features at least two characters, either pitting them against one another or having them working toward a shared goal. This mirrors our lives, where we’re in contact with others daily, sometimes hourly. Sometimes every single moment of every single day.
Even the least social among us must rely on or deal with others. Unless we’re totally self-sufficient, someone else makes our clothing or our food or our mode of transportation or our homes.
We need other people.