When Deloria writes, “why is a remote Indian princess grandmother so necessary for many whites?” and then offers white guilt and xenophobia, and the “white man” love of royalty as theories, he seems to take off his historian hat and become an armchair psychologist. He ignores the complexities of relations between whites and Indians, especially on the Pennsylvania frontier in the early 18th century. First, “whites” is pejorative that deliberately overlooks the very real and very important differences between Dutch, Scandinavian, French and English; Christian sectarian attitudes; and economic and social class attitudes toward Native Americans. It overlooks just how intertwined early frontier colonial and Native American life was, in favor of an easy answer. He also suggests that Jews don't claim Native American ancestry because they themselves are tribal, but to me, it seems more likely that it's because the bulk of America's European Jews didn't emigrate until the Indian wars were over.
I guess my point is that while I too have met many people who claim (mostly erroneously) that they have Indian blood, I think it has less to do with the reasons Deloria gives and maybe more to do with our frontier heroes' adoption of Native American customs and our strong oral tradition celebrating them. After all, Daniel Boone was adopted by the Shawnee and toward the end of his life he said, "'while he could never with safety repose confidence in a Yankee, he had never been deceived by an Indian,' and that if he had to choose, 'he should certainly prefer a state of nature to a state of civilization... I am very sorry to say that I ever killed any [Indians], for they have always been kinder to me than whites.'" (from John Mack Faragher's Daniel Boone 300)
Or am I way off base and should just shut up?
especially on the Pennsylvania frontier in the early 18th century.
True, but Deloria isn't writing about early 18th century Pennsylvania. He's writing from the perspective of the late 1960s. Those distinctions between whites hadn't mattered for quite some time by then, and from his perspective, those differences were never as great or as lasting as the conflicts between any group of whites and Indians. It's worth noting that there are no Indian reservations in Pennsylvania today.
If you dig deeper into Native American studies, you'll find a recurring theme of "detribalized" whites who turn to Native American traditions for their own identity. This was the impetus behind the Camp Fire Girls, an early Scout-like group, and the Boy Scouts of America themselves. In fact, in the late 19th and early 20th centuries there was a sort of "back to nature" movement that idealized Native American life as being rugged and masculine, as opposed to the effete, urbanized modern American man. (See: Jared Farmer, On Zion's Mount) Although I think you're right about the Indian Wars being over before most Jewish emigration happened, his point is about a tight-knit, "tribal" community that people with family spread all over the country, or without deep ties to their own heritage, might not feel.
As a historian and resident of the Southwest, I don't really see the oral tradition celebrating Indians quite like you do. In the plaza of Santa Fe, they had to remove the word "savages" from a Civil War/Indian Wars memorial - this stood for decades in the heart of town. Deloria published his book in 1969 - the year before, Indians were finally allowed to vote in Arizona and New Mexico. Kit Carson has towns and a forest named for him, while many Native Americans consider him (with a good deal of merit) to be a cold-hearted killer. These killings were celebrated for many years in the press with some of the first mass-published, cheap paperbacks, and their heritage lasted well into the 20th century with B-movie westerns (and plenty of A-list actors) killing Indians left and right - one of John Wayne's biggest films was about a man who wants to kill his daughter, because she had "gone Native" after being kidnapped. Indians schools in this country were dedicated to the idea that they "kill the Indian and save the man" - not quite the experience of, say, Belgian immigrants, or Lutherans. While Daniel Boone may have said some nice things, here's what happened after the Sand Creek Massacre: "When someone questioned [commanding officer Col. John] Chivington's policy of killing children, he said, 'Nits breed lice.' Chivington returned to Denver in triumph. At a theater his men paraded their war trophies before the cheering crowds: Scalps, fingers, tobacco pouches made from scrotums, purses of stretched pudenda hacked from Cheyenne women. The Denver newspapers praised the Colorado Volunteers for their glorious victory." (Hampton Sides, Blood and Thunder, another book I would highly recommend.)
There may be a strain of admiration for Native Americans underlying a lot of American thought, but it's hard to argue that there wasn't a more overpowering racism resulted that resulted in mass disenfranchisement, loss of treaty-guaranteed land and rights, forced relocations, forced boarding schools, and treating Native Americans as mascots, exhibits, and souvenirs (see Leah Dilworth, Imagining Indians of the Southwest). The U.S. Army in the 1860s issued standing orders to all frontier medical officers to be vigilant to collect and send East any and all Native American remains; graves were robbed and some Indians were outright murdered for this purpose.
I would heartily recommend Vine's son Phil Deloria's excellent Playing Indian. You may find his work more reasoned and nuanced than his father's.
Also, you should not shut up. We are nowhere if we don't keep thinking and exploring.