The Iliad was likely written in the 700s or 600s BCE however it deals with stories of a real war in the 1100s or 1200s BCE So the Iliad is based on earlier sources.
The same can be said for the book of Kings. The material in the acts of the kings of Judah or the acts of the kings of Israel are documents that possibly come from the exilic period and even those would be based on court records. (We know this because some of the Kings and events mentioned in those works line up with history)
Now coming to Ovid. You are right in that he wrote in the first century BCE. The story of Baucis and Philemon is contained in a large work called Metamorphoses. (Book VIII) https://david-drake.com/2013/metamorphoses-baucis-and-philemon/
The stories contained in Metamorphoses are far older than Ovid. Hesiod doesn't have the story in the 700s BCE so the original story could have spanned anywhere between 700-100BCE
I believe Genesis was written in the supplementary form in the 200s BCE however even ultra-conservative scholars that date the composition of Genesis in the Persian period are still well within that range, However minimalist dates like mine allow Greek influence.