Many US historians are liars. They know the truth, but then they lie about it, to minimize the racism. Because it's is shameful.
It's not hard to find primary sources on Susan B Anthony's correspondence and conversations with Frederick Douglass, and Ida B Wells. It's not hard to find out exactly how many Black women were invited to Seneca Falls. It's not hard to confirm that she literally opposed the 15th amendment, because she didn't want Black men to get the vote first.