This sounds like you're basically asking what modern-day ethnic group descends from the "indigenous" people of the Levant? I mean, we can't compare Canaanite DNA to prove that Palestinians are descended from them directly, no.

Genetic studies have shown repeatedly that Jewish populations from all over the world are closely related to Palestinian Arabs (as well as Syrians and Jordanians, unsurprisingly). This has lead some historians to theorize that Palestinian Muslims may be at least partially descended from Jews who remained in Palestine during Roman times by converting to Christianity, and then eventually converted to Islam.

But what about the Canaanites?

Mark Smith in The Early History of God: Yahweh and Other Deities of Ancient Israel states, "Despite the long regnant model that the Canaanites and Israelites were people of fundamentally different culture, archaeological data now casts doubt on this view. The material culture of the region exhibits numerous common points between Israelites and Canaanites in the Iron I period (ca. 1200–1000 BC). The record would suggest that the Israelite culture largely overlapped with and derived from Canaanite culture... In short, Israelite culture was largely Canaanite in nature. Given the information available, one cannot maintain a radical cultural separation between Canaanites and Israelites for the Iron I period." (pp. 6–7).Smith, Mark (2002) The Early History of God: Yahweh and Other Deities of Ancient Israel, (Eerdman's)

It's not a leap to suggest that the fight between Israelities and Caananites was a religious conflict between the same ethnic group, and that the Biblical account is the mythology that the emerging Jewish religion created for itself to separate itself from the pagans in the area. Given that we know that there were proto-Jewish worship of the "consort of Yahweh" at tree altars this makes sense.

So basically, both modern Jews and Palestinians are very likely descended at least partially from the group that the bible referred to as Canaanites.

It is worth noting that during the Levant's long history of colonial occupation, occupying forces brought in various populations as well. As recently as the 20th century under the British mandate, many Arabs from other countries and people from Eygpt were brought in as laborers, for example. So many people that today we'd call Palestinians descend from those groups as well. Likewise, despite the strong religious and cultural prohibitions against intermarriage, genetic evidence shows clearly that in the diaspora, Jews did intermarry with the local populations. The genetic evidence suggests that far more non-Jewish women converted to Judaism than was previously thought.

Isn't the Palestinians descendants of the Sea peoples?

I'm surprised this thread does not mention the Samaritans.

Clearly, their cultural ancestry can be traced back to the same time frame of the Canaanites, and their religiously-driven isolationism provides reasonable assurance that their biological ancestry is just as "pure".