Regarding the argument of the land of our forefathers — without the religious argument that the land was given to us by the Holy One, blessed be He, there is something problematic about this argument. We were not the first ones here; there were already peoples here before us, and we fought them and conquered their land. What is the difference? That those peoples no longer exist? Because if that is the only difference, then we have no more right to the land than anyone else who claims ownership of it. And if someone expels us from the land, then he will have a right to it exactly like our right — everyone expelled whoever was there before him.

I completely disagree with Michi’s answer. The claim that we are like any people that wants sovereignty for itself may be true, but it is not the main point. The important question for any people is: on what basis is it entitled to that sovereignty? The answer in the case of the Jewish people is so simple and “primitive” that I do not understand how it can be interpreted otherwise.

Judaism’s supreme norm is anchored in the Torah, and the principle of the promise appears there explicitly. Of course, that promise does not have to be interpreted in modern national terms, but from there to the claim that we have a right to the land without the Hebrew Bible, the road is still very long.
Our forefathers believed in that promise (even if it is entirely fiction and there is not even a God to make such a promise…), and so it was on the basis of that belief as well that Zionism was created for the Jews, and not, say, for the Japanese or the Circassians…

Doron, according to what you are saying, no people has national rights anywhere. Of course the Hebrew Bible strengthens our right to be here, but even without it the right exists.

Exactly the opposite. Rights in general, and specific national rights, are built on a very complex system of cultural, historical, political, and other justifications. Each case has to be judged on its own merits.

Therefore, Zionism historically and factually built its rights on that very system, at the foundation of which stands the Hebrew Bible. On its own terms, it could not be otherwise.
In your wording: very few peoples — if any — have a document “that strengthens their right” to any particular territory.