I–V–vi–IV is just a chord progression. Using it does not make a song unoriginal. You can build a billion melodies on it in just one mode of a scale. Then there's all the other stuff: instrument choice, arrangement, rhythm, lyrics (if you have them).

A song is so much more than a chord progression.

For those playing along at home: modern pop favorite I–V–vi–IV is also the chord progression used in some arrangements of the 1788 classic Auld Lang Syne.