It's a little hard to speculate about the intent of a series of writers who were active thousands of years ago. The Bible contains so many different authors, writing at different times and in different contexts, that it's possible to find nearly anything if you look hard enough and can employ sufficient interpretive creativity to the text.

Generally speaking, the portions of the Bible that have been used to justify slavery, Jim Crow/Segregation and Apartheid are found in the Old Testament. The New Testament is obviously dominated by the presence of Jesus, who, at least in the parable of the Good Samaritan, advances a very progressive sense of racial equality. This stands in stark contrast to the racial ideology of the society in which he lived. The Jewish elite of his time very much viewed themselves as God's chosen people, which in turn made everyone else not-chosen people and thus inferior. There's a great deal of writing concerning the place and value of the Gentile (non-Jew) in Talmudic law, with some going so far as to justify the killing of non-Jews and classifying them as animals.

While there is very little that extreme in the Old Testament, there is a scriptural basis for that line of thinking. The Old Testament is a product of a tribal society, and a tribe which strongly sought to delineate itself from its neighbors, with whom violent conflict was very common. Given that context, it's easy to see how a sense of Hebrew racial supremacy would arise. 'God chose us; he didn't choose you; we're locked into an existential struggle with you, so I'm going to view my people as inherently better than you as a way to contextualize this conflict.'

In that sense, the authors of certain parts of the Bible most certainly did intend for their writing to have a racial/ethnic/tribal supremacist ideology.

Oddly enough though, to a white slave owner in 1850s Alabama, the authors of these racist texts and the objects of their racism would have been nearly indistinguishable. They all would have been non-white and non-Christian.

One of the primary themes of white, Christian scriptural justification for racial supremacy is found in the book of Genesis. It contains multiple passages which refer to the sin of a father being passed on to his descendants (even though this concept is explicitly rejected by Jesus in the New Testament). There are two particular sinners that are frequently used in this context. Cain, son of Adam and Eve, who murdered his brother Abel, was cursed by God with a 'mark' to label him as a murderer. Although what that mark would be is unclear. That mark has been interpreted by some white Christians as being black skin. Thus all people with black skin are descendants of Cain and, as such, are cursed by God and not entitled to the same treatment as others.

The other scriptural case of a bloodline being cursed by God is that of Noah's son Ham and his son Canaan. Ham committed some type of indiscretion, and his punishment was to be stripped of his birthright and condemned to slavery. Not only would this punishment apply to him, but all of his descendants as well. Somewhere along the line, it was decided that Ham and Canaan's descendants were the people of Africa, and thus ordained by God to be slaves.

On top of the purely Scriptural basis for racial supremacy, Christian theology has produced its own more intellectual justifications as well. Apartheid directly stems from the Dutch Reformed theology of the Afrikaners and has its origins in the Afrikaner church.