Question: Where did the term Palestine come from and are they descendant from the Philistines of the Bible?
Answer:
السلام عليكم ورحمة الله وبركاته
From my humble understanding, the philistines were a group that lived during the time of the Children of Israel and who the earlier prophets were originally asked to fight as per the Bible. Eventually this group disappeared, however people, such as the Greeks and later the Romans, began referring to the area as Palestine or something similar probably due to the Philistines who lived there. Thus the area and people living in it came to be called Palestine and Palestinians respectively, not because they necessarily descended from the Philistines, but because the area became known as Palestine because people were familiar with the Philistines.
That being said, it is possible that they are descendants. DNA tests may possibly prove that.
Open to correction
Jazakallah khayra