Why there are so many different accounts about "Paris" in mythology?

Answer 1

Of which Paris do you ask? Paris, Trojan Prince, Son of King Priam, Seducer of Helen of Troy? Just like all the other mythic characters associated with the Trojan war, elements of his life story have been told and retold from before the time of Homer (approx. 800 bce) through the golden age of Athens (approx 400 bce).

Answer 2

Mythology is mostly oral tradition. Different storyteller slightlu different tale. It also depended which side you were rooting for.