It’s not, though. It may have become more widespread and documented as “Palestine” because of the Romans/Greeks transcribing just before the common era, but the root PLST is documented from over three thousands years ago in Egyptian text as well as in Assyrian text. Djahi, Retenu, Canaan are also names, but the indigenous people also made use of something along the lines of PLST (or the variants transcribed we have documented) in the area, which then gained the most international recognition.
(2/2) the name palestine comes from this history yes. but the name is not from indigenous continuity, it was to erase jewish ties to the land by roman colonizers. modern palestinians dont descend from philistines but from arabization. filastin derives from latin. so it’s still a name derived from colonization.