You’re accusing someone of not knowing the history of the region whilst simultaneously pretending that Palestinians aren’t/weren’t real, and that Israel wasn’t established in 75 years ago…
I suppose the fact that only 10% of those living in Palestine in 1922 were Jewish, even after a considerable Jewish immigration in the preceding years, is of no interest to you. The other 90% of inhabitants of Palestine were Muslim and Christian.
Palestinians have existed in Palestine for millennia. They have strong genetic links to the Canaanites.
If you’re wanting to go back to the times of Judea and the Israelites, then you’re also ignoring the fact that there would have been Jewish Palestinians who converted to Christianity and/or Islam over time, because of the empires that have been present in the region.
Meaning that yes, most of modern-day Muslim Palestinians were actually likely Jewish historically! The same applies to Christian Palestinians.
Palestinians are actually not Arabs ethnically, they only identify as such due to language, religion and culture. The same is true of modern day Egyptians, who are also not ethnically Arab, but identify as such due to language, religion and culture.
For lack of a more accessible website on the subject, you can read about Palestinians on Wikipedia: https://en.m.wikipedia.org/wiki/Palestinians#DNA_and_genetic_studies