It's a fundamental misunderstanding of what "indigeneity" is to believe that it means "whoever has the oldest claim to the land." Rather, to describe a people as "indigenous" is a reference to their current relationship to the government and to the land—namely that they have been or are being dispossessed from that land in favour of other private owners (settlers); they have a separate, inferior status to settlers according to the law, explicitly; they are shut out of institutions created by the settler state, explicitly; they are targeted implicitly by the laws of the settler state (e.g. Israeli prohibitions against harvesting wild thyme or using donkeys or horses for transportation); the settler state does not punish violence against them; &c. &c.
It is a settler-colonialist state that creates indigeneity; without one, it is perfectly possible for immigrants to move to and live in a new location without becoming settlers, with the superior cultural and legal status and suppression of a legally inferior population that that entails.
If all that were going on were some Jewish people feeling a personal or religious connexion to this land and wanting to move there, accepting the existing people and culture and living with them, not expelling and killing local populations and creating a settler-colonialist state that privileges them at the expense of extant populations, that would be a completely different situation. But any assertion of the land's fundamental Jewish-ness (really they mean white or European Jewishness—the Jewish Arabs who were already in Palestine never seem to figure in these arguments) is a canard that distracts from the fundamental issue, which is a people's right to resist dispossession, ethnic cleansing, and genocide.
So, what does this all mean for Palestine?
Absolutely nothing.
Although the argument has many ahistorical assumptions and claims, it is not these which form its greatest weakness. The whole argument is a trap. The basic implication of this line of argumentation is as follows:
If the Jewish people were in Palestine before the Arabs, then the land belongs to them. Therefore, the creation of Israel would be justified.
From my experience, whenever this argument is used, the automatic response of Palestinians is to say that their ancestors were there first. These ancestors being the Canaanites. The idea that Palestinians are the descendants of only one particular group in a region with mass migrations and dozens of different empires and peoples is not only ahistorical, but this line of thought indirectly legitimizes the original argument they are fighting against.
This is because it implies that the only reason Israel’s creation is unjustified is because their Palestinian ancestors were there first. It implies that the problem with the argument lies in the details, not that the argument as a whole is absolute nonsense and shouldn’t even be entertained.
The ethnic cleansing, massacres and colonialism needed to establish Israel can never be justified, regardless of who was there first. It’s a moot point. Even if we follow the argument that Palestinians have only been there for 1300 years, does this suddenly legitimize the expulsion of hundreds of thousands? Of course not. There is no possible scenario where it is excusable to ethnically cleanse a people and colonize their lands. Human rights apply to people universally, regardless of whether they have lived in an area for a year or ten thousand years.
If we reject the “we were there first” argument, and not treat it as a legitimizing factor for Israel’s creation, then we can focus on the real history, without any ideological agendas. We could trace how our pasts intersected throughout the centuries. After all, there is indeed Jewish history in Palestine. This history forms a part of the Palestinian past and heritage, just like every other group, kingdom or empire that settled there does. We must stop viewing Palestinian and Jewish histories as competing, mutually exclusive entities, because for most of history they have not been.
These positions can be maintained while simultaneously rejecting Zionism and its colonialism. After all, this ideologically driven impulse to imagine our ancestors as some closed, well defined, unchanging homogenous group having exclusive ownership over lands corresponding to modern day borders has nothing to do with the actual history of the area, and everything to do with modern notions of ethnic nationalism and colonialism.
I would also be careful about mentioning a sense of "nationhood" or "national identity" in this context, as it could seem to imply that people need a "national" identity (a very specific and very new idea) in order not to deserve genocide. Actually the idea that Palestinians lacked a national identity (of the kind that developed in 19th-century Europe) is commonly used to justify Zionism. Again from Decolonize Palestine:
This slogan ["A land without a people for a people without a land"] persists to this day because it was never meant to be literal, but colonial and ideological. This phrase is yet another formulation of the concept of Terra Nullius meaning “nobody’s land”. In one form or the other, this concept played a significant role in legitimizing the erasure of the native population in virtually every settler colony, and laying down the ‘legal’ and ‘moral’ basis for seizing native land. According to this principle, any lands not managed in a ‘modern’ fashion were considered empty by the colonists, and therefore up for grabs. Essentially, yes there are people there but no people that mattered or were worth considering.
There is no doubt that Zionism is a settler colonial movement intent on replacing the natives. As a matter of fact, this was a point of pride for the early Zionists, as they saw the inhabitants of the land as backwards and barbaric, and that a positive aspect of Zionism would be the establishment of a modern nation state there to act as a bulwark against these ‘regressive’ forces in the east [You can read more about this here].
A characteristic feature of early Zionist political discourse is pretending that Palestinians exist only as individuals or sometimes communities, but never as constituting a people or a nation. This was accompanied by the typical arrogance and condescension towards the natives seen in virtually every settler colonial movement.
That the early settlers interacted with the natives while simultaneously claiming the land was empty was not seen as contradictory to them. According to these colonists, even if some scattered, disorganized people did exist, they were not worthy of the land they inhabited. They were unable to transform the land into a modern functioning nation state, extract resources efficiently and contribute to ‘civilization’ through the free market, unlike the settlers. Patrick Wolfe’s scholarship on Australia illustrates this dynamic and how it was exploited to establish the settler colony.