It wasn`t such a long time ago when whoever was in command was called the pilot. When anyone happened to ask who is in charge of the flight the reply would have been "the pilot", not the pilots. The young one next to him was the pilot`s assistant, an apprentice who like most was learning the job, every aspect of it. It took many years to become "the pilot".
Now that we have a captain, a first officer and a computer all trying to do the same job, if you ask the same question the reply would be "the computer and sometimes the pilots and always the pilots when anything goes wrong".