Darwin made virtually no mention of humans at all in his 1859 work "The Origin of Species." Further, popular political writing 150 years ago and even later commonly used "race" to mean nationality; we read from those times about the "Irish race" and the "English race." In fact, Darwin considered all human biological variation he observed in his worldwide travels merely due to differences in climate and diet. For example Charles Darwin, wrote in The Descent of Man, and Selection in Relation to Sex (John Murray, London, 1871), "It may be doubted whether any character can be named which is distinctive of a race and is constant." And later on pg: 226, 1st edition, “But the most weighty of all the arguments against treating the races of man as distinct species, is that they graduate into each other, independently in many cases, as far as we can judge, of their having intercrossed. Man has been studied more carefully than any other organic being, and yet there is the greatest possible diversity amongst capable judges whether he should be classed as a single species or race, or as two (Virey), as three (Jacquinot), as four (Kant), five (Blumenbach), six (Buffon), seven (Hunter), eight (Agassiz), eleven (Pickering), fifteen (Bory St. Vincent), sixteen (Desmoulins), twenty-two (Morton), sixty (Crawfurd), or as sixty-three, according to Burke.(17) This diversity of judgment does not prove that the races ought not to be ranked as species, but it shews that they graduate into each other, and that it is hardly possible to discover clear distinctive character between them.”
Samuel George Morton, mentioned above measured the volume of 256 skulls from around the world by pouring white pepper seed into each cavity, then gauging in cubic inches the volume of seed needed to fill a sample. From that work, he published Crania America in 1839 judging the "mental capacity” of entire populations from a few skulls. Darwin dismissively wrote in Descent of Man, Vol 1 page 145, “As the various mental faculties were gradually developed, the brain would almost certainly have become larger,” and concluded by dismissing Morton's racism, “On the other hand, no one supposes that the intellect of any two animals or of any two men can be accurately gauged by the cubic contents of their skulls.”
Morton was a “fifth day creationist” claiming that non-white races were created with "beasts of the field" on the Fifth Day of the Genesis Creation account. Harvard professor Louis Agassiz (1807-1873) was also a “fifth day” supporter. Darwin not only correctly pointed to our common ancestry with African apes, but concluded, "It may be doubted whether any character can be named which is distinctive of a race and is constant."
Creationists would not need to lie if they could provide facts.
In fact, Frederick Douglass's 1854 commencement speech to WESTERN RESERVE COLLEGE titled "The claims of the Negro, ethnologically considered," detailed the "scientific" racism of "Messrs. Nott, Glidden, Morton, Smith and Agassiz." All pro-slavery Christian creationists.
A contrasting example was the Rev. John Bachman (February 4, 1790 – February 24, 1874). He was an American Lutheran minister, social activist and naturalist who collaborated with J.J. Audubon. Co-founder of Newberry College, and Lutheran Theological Southern Seminary, Bachman published in 1850 “The Doctrine of the Unity of the Human Race Examined on the Principles of Science,” and in 1855 “Characteristics of Genera and Species, as Applicable to the Doctrine of Unity in the Human Race.” Bachman was liberal of his place and time. He accepted that the African, and Caucasian races were of the same species. However, he also wrote that the African were of such an inferior, and debased nature that it was the Christian Duty of Whites to enslave the Africans “for their own good.”
Instead of reading nonsense, I recommend;
Daly, John Patrick 2002 "When Slavery was Called Freedom: Evangelicalism, Proslavery, and the Causes of the Civil War" University of Kentucky Press.
Robert J. Richards 2013 "Was Hitler a Darwinian? Disputed Questions in the History of Evolutionary Theory," University of Chicago Press.