Whether or not any Jews have ancestors in the area (and there's much evidence the arab ancestors pre-date them) has no relevance on their right to land.
Do you have proof of these arab ancestors who pre-date the Jews?
Prior to the arrival of the Jews the land of Israel was ruled by the Canaanites and prior to them we have no clue who lived or ruled that area.
The Arabs, as an ethnic group, didn't enter the area to much later (622-633) during the Muslim conquests.
Genetically though the Palestinians and the Jews are very closely related and that the Palestinians themselves are probably descendants of the Jews and Christians who lived in the area prior to the arrival of Islam.
Also, the Jews are probably more closely related to Palestinians than they are to Europeans. So the idea of sending them back to where they came from is kind of foolish since they did in fact come from Israel.