What is a metaphor in American Pie by Don McLean?

its not hard to find google search something like: metaphors in American pie and it will come up with a variety of websites full with lyrics and the reasons behind them the websites usually have the same content so it doesnt matter what you choose.

The song is a contrbute to the death of buddy holly, the big bopper and ritchie valens who died in plane crash in 1959.