But they were born on this soil also, so they would be NBC and no need for the 14th...
Of course under that theory they would not have been NBC either, but since no former slave ever ran for the Presidency the point is moot.
Actually the reason the 14th Amendment was required was because of the Supreme Court’s Dred Scott decision. Roger Taney in writing the majority opinion basically said a black person(slave or free) was not, had never been, and could never be a citizen of the United States. 14th made that ruling mute.
Indians were not made Citizens under the 14th either, how about that.