"They have also, in their infinite Western wisdom, sent us a blind boy for one senator, and an Indian -- an Indian! -- for another."
This was very different from the attitudes toward blacks in the U.S. in 1907. Latins who were somewhat black like the Dumas novelists, father and son, were okay as long as there wasn't much talk about it (e.g., some partly black Cubans broke the major league baseball color line playing for the Washington Senators in the late 1930s and early 1940s long before Jackie Robinson, but almost nobody mentioned it, so it wasn't a Thing). A few politicians were a little bit black (various Southern legislatures drawing up Jim Crow laws in the late 19th Century avoided "one drop" definitions to not disqualify some of their members). But it wasn't to be talked about, while Senator Owen or Vice President Charles Curtis being partly Indian was celebrated.
The causal mechanism was the reverse of what we are supposed to believe now. We are always being told that white bigotry against blacks was driven by "hate," but 19th Century whites had hated Indians far more than they had hated blacks. Just about everybody who contact with Indians on the frontier hated them, with only a few exceptions (e.g., Sam Houston), while most whites who came into contact with black slaves liked them. Mark Twain is extremely representative: compare Jim in Huckleberry Finn to Injun Joe in Tom Sawyer.