"Avraham and his ancestors originated beyond the Euphrates River in the lands of Aram. Avraham and his earliest descendants sojourned in the land of Kena'an as strangers. Am Yisra'el received the Torah at Har Sinai and learned to observe much of it in the wilderness, all outside the land. Then Am Yisra'el conquered the land from the Kena'anim and established Torah law over the conquered lands and peoples. This is what the Torah, the Prophets, and the Sages unapologetically affirm.
The millennia of Jewish history as strangers before conquest and as rulers after, the centuries of Jewish kingdoms and Temples, the feeling of a deep connection to the land, Jews should know and be proud of these things, but none of it has anything to do with being indigenous. Jewish people, culture, language, etc. developed in Bavel no less than anywhere else, but that does not make Jews indigenous to Bavel either.
The idea that the Kena'anim were conquering Eretz Yisra'el from the descendants of Shem in the days of Avraham seems to find little support outside of Rashi's comment on Genesis 12:6, even elsewhere in his own commentary. For instance, in his commentary on Numbers 13:22, Rashi indicates that Hevron was built by Ham for Kena'an, rhetorically asking if it is possible that Ham built Hevron for Kena'an, his youngest son, before he built Tzo'an for Mitzrayim, his eldest.
More explicitly, in his commentary on Genesis 1:1 and Psalms 111:6, Rashi reminds us that HaShem, the Creator of the earth, gave the land to the Kena'anim before He took it from them and gave it to Yisra'el:
"Rabbi Yitzhak said, "It was not necessary to begin the Torah except from “This month is to you” (Exodus 12:2), which is the first commandment that Yisra'el was commanded. Now for what reason did He commence with “In the beginning?” Because of [the verse] “The strength of His works He related to His people, to give them the inheritance of the nations” (Psalms 111:6). For if the world should say to Yisra'el, “You are robbers, for you conquered by force the lands of the seven nations [of Kena'an],” they will reply, "The entire earth belongs to the Holy One, blessed be He; He created it and gave it to whomever He deemed proper When He wished, He gave it to them (the Kena'anim), and when He wished, He took it away from them and gave it to us (Yisra'el)." (Rashi on Genesis 1:1)
"When He gave them (Yisra'el) the inheritance of the nations (Kena'anim), He let them know His strength and His might. And Midrash Tanhuma (Buber, Genesis 11): He wrote for Yisra'el [about] the Creation to let them know that the earth is His and that it is in His power to settle in it anyone He wishes, and to move these out and settle others, so that the nations will not be able to say to Yisra'el, “You are thieves, for you conquered the land of the seven nations [of Kena'an].” (Rashi on Psalms 111:6).
This does not say that the nations will not say Yisra'el are thieves. They do, and will continue to say this. Just as they say it when it comes to the particular locations of the Cave of Makhpela, the tomb of Yosef, and the Temple Mount, which were purchased by Avraham, Ya'akov, and David. The point is that Yisra'el should know better than to be convinced by or get sucked into the arguments of the nations. Because it is to Yisra'el that HaShem relayed His creation of the world, and to Yisra'el that He chose to give the land with the conditions of the Torah.
That Avraham and his descendants dwelled in the land of Kena'an as strangers is explained in Rashi's commentary on 15:13: "It does not say, “[strangers] in the land of Mitzrayim,” but “[strangers in a land] that is not theirs,” and from the time Yitzhak was born (Genesis 21:34): “and Avraham sojourned, etc.” (Genesis 20:1): “And [Yitzhak] sojourned in Gerar.” (Psalms 105:23): “And Ya'akov sojourned in the land of Ham.” (Genesis 47:4): “To sojourn in the land we have come.” - [from Midrash Abchir]"
Ramban also explained that the Avot dwelled as strangers in the land in his commentary on Genesis 37:1: "The explanation for "and Ya'akov settled in the land of his father's sojournings" (Genesis 37:1) is that [Torah] is saying that the chiefs of Edom settled "in the land of their inheritance" (Genesis 36:43), the land that they took for themselves as an eternal inheritance, but Ya'akov dwelt as a stranger, as his fathers [Avraham and Yitzhak] did, in a land that was not theirs but Kena'an's. And the intention is to tell us that they [Ya'akov, Yitzhak, and Avraham] chose to sojourn in the chosen land. And it tells us that, "that your offspring shall be aliens in a land not their own" (Genesis 15:13) was fulfilled through them [Ya'akov and Yitzhak], and not Esav. For it was through Ya'akov alone that offspring was considered theirs [Avraham's and Yitzhak's]."
Contrary to the claim that Ramban explains the journey of Avraham's family to the land of Kena'an as a return to their homeland, Ramban explains in his commentary on Genesis 11:28 that Avraham and his fathers had always dwelled beyond the Euphrates River prior to Avraham:
"It is written, "Beyond the [Euphrates] River your forefathers always dwelled" (Joshua 24:2), and the word "always" (me'olam) implies that his forebears had always been there. And it is written, "I took your father Avraham from Beyond the River (me'Ever HaNahar)" (Joshua 24:3) ... Rather, the truth is that their native land was the land of Aram, in the area known as Beyond-the-River (Ever HaNahar), and that was [Avraham's] ancestral inheritence from antiquity. As Scripture says of the descendants of Shem, "Their dwelling place extended from Mesha going toward Sefar, the mountain to the east" (Genesis 10:30), the "mountain of the east" being a general name for a large area, as is written of the descendants of Shem, "in their lands by their nations" (Genesis 10:31). And it is written, "From Aram did Balak, king of Mo'av, lead me, from the mountains of the east" (Numbers 23:7). Thus you see that he (Avraham) and his fathers were from that land (Aram) from antiquity." (Ramban on Genesis 11:28)
And in his commentary on Genesis 14:18, Ramban brings up and dismisses Rashi's interpretation of Genesis 12:6 (that the Kena'anim were conquering the land from the descendants of Shem) based on the peshat of the Torah, which explicitly describes the land as belonging to the Kena'anim prior to Avraham:
"According to our Sages (TB Nedarim 32b), who say that Malki Tzedek was Shem ben-No'ah, he went from his land to Yerushalayim to serve HaShem there, and was a kohen to the Supreme God for them (the Kena'anim), because he was the venerated brother of their father (Ham), for Yerushalayim was always within the border of the Kena'ani. Rashi wrote above [regarding] "the Kena'ani was then in the land" (Genesis 12:6): "[the Kena'ani] was going and conquering the land of Yisra'el from the offspring of Shem, ancestor of Avraham, for it fell in the portion of Shem when No'ah apportioned the earth to his sons, as it says, "and Malki Tzedek, king of Shalem" (Genesis 14:18)." But this is not correct, for "the border of the Kena'ani extended from Tzidon [going toward Gerar, as far as Aza, going toward Sedom, Amora, Adma, and Tzevoyim, as far as Lasha]" (Genesis 10:19) encompassing all of the land of Yisra'el, while the border of Benei Shem was east of Mesha (Genesis 10:30), far from the land of Yisra'el. But if No'ah apportioned the lands to his sons, and gave the land of Yisra'el to Shem, it was as "one who apportions his possessions by his mouth [for distribution after his death]" (a phrase used in TB Bava Batra 126b), and Benei Kena'an would dwell in it until HaShem would endow it to the offspring [of Avraham] who loved Him, as I have mentioned [on Genesis 10:14]."
In other words, while HaShem always intended to eventually give the land to Shem's descendants, the land belonged to the Kena'anim in the days of Shem, Avraham, Yitzhak, Ya'akov, and his descendants, who went from their own lands to dwell in the land as strangers, until He brought Yisra'el out of Mitzrayim, and brought them into the land to conquer it from the Kena'anim. That Yosef refers to "the land of the Ivrim" in Genesis 40:15 does not change that he and his fathers all sojourned in the land as strangers, just as Yisra'el did in the land of Goshen, which was known to be their dwelling place in Mitzrayim.
But even if, for the sake of argument, the nations were convinced that Jews are indigenous to the land, what tangible results do those who push this argument envision? Do they expect these nations to then conclude that the descendants of pre-state and pre-modern aliyot non-Jewish communities are not indigenous, or are less indigienous than Jews? Do they expect the nations to accept the annexation of Yerushalayim and Golan? Do they expect the nations to expect continued military rule of Yehuda and Shomron?
A majority of voting nations supported the establishment of Jewish and Arab states between the Jordan and Mediterranean long before this indigenous fad, and they will continue to demand the establishment of an Arab state in Yehuda, Shomron, and Aza whether they argue that the Arabs are indigenous or not. No matter how you slice it, they demand an Arab state next to Israel, and will not be convinced otherwise by any argument. And those who demand an Arab state on Israel's ruins will not be convinced by any argument either."