You know that part of Huckleberry Finn where his dad goes on a racist tirade? That was actually criticism of poor whites being ok with their shit conditions simply because they could look down on black people. Twain was based as fuck for his time period.
Of all the shit you could call Mark Twain out on, treatment of African Americans isn't one of them. His books humanized them, despite his upbringing in a community where slavery was ordained by the church and state, and his father owning several as well. As he grew older, those views became more and more apparent.
He's required reading material in a lot of Critical Race Theory courses.