Palestinaisns had a permanent presence.
Really? Since when? Are you implying that modern day Palestinians (an Arabic race) are direct descendants of the Philistines? If you are using the Bible as your argument, are you aware of the meaning/etymology of the word?
This is a really interesting subject in and of itself.
Nothing is known for certain about the original language or languages of the Philistines, however they were not part of the Semitic Canaanite population. There is some limited evidence in favour of the assumption that the Philistines were Indo-European-speakers either from Greece and/or Luwian speakers from the coast of Asia Minor. Philistine-related words found in the Bible are not Semitic, and can in some cases, with reservations, be traced back to Proto-Indo-European roots. By the beginning of the 1st Millennium BCE they had adopted the general Canaanite language of the region.
Today, modern Palestinian shares about 60% of its words with Arabic. The rest is a combination of vocabulary from several dead languages including Aramaic, syriac Turkish, as well as french and english cognates.
From wiki again:
The area where Levantine Arabic is spoken used to speak Canaanite languages (Eblaite, Ugaritic, and then Hebrew-Phoenician, characterized by shift of semitic /a/ to /o/ and /?/ to /š/). It had then adopted the more Western Aramaic in the middle of the 1st millennium BC, generalized as official language by the Persian Empire. Alexander the Great conquered the area, which was then taken by the Romans. Just before arabization, the region certainly counted a significant number of Greek speakers as a part of the Byzantine empire.
Philistines probably became assimilated to some degree and later arabized along with most the other cultures in the region
After the rise of Islam in the Arabian Peninsula, Arab culture and language spread through trade with African states, conquest, and intermarriage of the non-Arab local population with the Arabs, in Egypt, Syria, Palestine, Iraq and the Sudan. The peninsular Arabic language became common among these areas; dialects also formed. Also, though Yemen is traditionally held to be the homeland of Arabs, most of the population did not speak Arabic (but instead South Semitic languages) prior to the spread of Islam.
While it is silly to imply the people that now live in the levant are direct descendants of a particular ancient group or culture, it would be equally silly to say that arabization has stripped them of any connection at all.
As a side note: of all the dialects of "Arabic" IMO levantine has the the least in common with traditional and standard arabic. This includes Lebanese and Palestinian dialects, which are very closely related (with some exceptions not worth going into).
My opinion is the "Palestinians" have nothing to do with the Philistines, at least not directly. They are likely called Palestinian because they lived in the region of the Levant historically known as Palestine (biblical and historical reasons for this) and they likely have a diverse and storied lineage which includes both semitic and Indo-European periods and influences. Regardless of what we call them and how accurate that term is, to me it is clear that they have been there in some fashion for a long time. Hell, Byblos or "jbiel" has been continuously inhabited for the last 8000 years or more. That is a damn long time.
Anyway, just my two pennies.