I believe that avatars are literal. It again and again reminds me how many zillions of years our earth has been around, (how many kalpas) and of the many wonders that have happened very long time ago that no more happens now, though we are provided with the facilities of the electronic age.
Blessed you are, to think of the holy Matsyavatara on the eve of Sri Janmashtami. (for our sect today is the eve of).
Do you agree with modern scientific thinking that the earth is about 5 billion years old and modern humans have been around for maybe only 100,000 years?