“they are a fake people – they are descendants of Lebanese and Syrians who came for economic opportunities”
That is completely untrue. None of these terms for nationalities were in use until late modern times; the earliest use of the term “Palestinian” appears to have been 1911; Syrian nationalism and Lebanese nationalism are both from the second half of the 19th century — and all three originated with Christians! But in any case the entire region was part of the Ottoman Empire. Moving from Damascus to Jerusalem was like moving from Baltimore to Boston. Not an issue at all. To call Palestinians “fake” with no right to live in the Land is the same kind of nonsense that we hear from Hamas when it insists that Israelis are colonialists! It is similar to telling me that I have no right to live in New York because I was born in Pennsylvania. (The latest twist on this is that the Trumpies will claim that I really was not born in Pennsylvania because my family moved to Maryland when I was a year old.)
Palestinian Arab Muslim families are big into geneology and many can trace their ancestry all the way back to early Ottoman times. This helps to facilitate cousin marriage, which is also very popular among Israeli and Palestinian Arabs. The Ottoman censuses found that the 16th century population was almost entirely Muslim, with few Christians or Jews, and population growth of Muslims is completely explainable through relatively low rates of natural increase.
The term “Palestinian” is older than that of most national identities. It is older than the term “Israeli”. We don’t have to come up with nonsense ahistorical arguments to justify Zionism. And we should not when they provide ammunition to our enemies.