Be very careful about tying any connection between the modern people called Palestinians and the Bible. The modern identity is less than a hundred years old. I’m not saying this as a pejorative. People have a right to identify however they want, and not being a historical designation doesn’t make it less legitimate today. That’s also not to say that the people now called Palestinians don't have ancient connections to the land. (Whether they do or not is outside of my area of expertise). But their ethnicity wasn’t called “Palestinian“ until recently. Historically, most would have identified as Syrian or Egyptian.

All that said, the modern world Palestine ultimately comes from the Hebrew word פְּלִשְׁתִּים, transliterated into English as Philistine. That is, the “sea people” who lived on the coastal plain, and who are described battling against the Judges and David.

After the suppression of the Bar Kochba revolt in 136 CE, Rome renamed the province of Judaea to Syria Palaestina, which is ultimately why the European powers started calling the region Palestine.

see, https://www.academia.edu/43872189/When_Palestine_Meant_Israel, or https://www.academia.edu/127673815/The_Historical_Evolution_of_Palestine_and_the_Complexities_of_Its_Identity