> This dates all the way back to the Constitution, which from the very start had a plain-text reading incompatible with slavery,
Heh. No. Not only was it, from the start, not “incompatible with slavery”, but it made direct accommodations for it and even explicitly protected the slave trade even against Constitutional amendments for a certain period.
From Art. I, Sec. 2: “Representatives and direct taxes shall be apportioned among the several states which may be included within this union, according to their respective numbers, which shall be determined by adding to the whole number of free persons, including those bound to service for a term of years, and excluding Indians not taxed, three fifths of all other Persons.”
Art. I, Sec. 9, cl. 1: “The migration or importation of such persons as any of the states now existing shall think proper to admit, shall not be prohibited by the Congress prior to the year one thousand eight hundred and eight, but a tax or duty may be imposed on such importation, not exceeding ten dollars for each person.”
Art. IV, Sec. 2: “No person held to service or labor in one state, under the laws thereof, escaping into another, shall, in consequence of any law or regulation therein, be discharged from such service or labor, but shall be delivered up on claim of the party to whom such service or labor may be due.”
Art V: “…no amendment which may be made prior to the year one thousand eight hundred and eight shall in any manner affect the first and fourth clauses in the ninth section of the first article;…”
> yet had a Bill of Rights conveniently not applied to slaves because everybody knew what the writers really meant by 'people'
Every article in the Bill of Rights is a limitation on the federal government, none protects against the states or against private parties, nor does any contradict and thus overrule the direct and indirect protections of slavery (including of the property interests of owners of fugitive slaves) and the slave trade written in the plain text of the original Constitution. People sometimes now, after the 14th Amendment, casually make imprecise reference to the Bill of Rights limiting the states, but it is actually the 14th Amendments limitations on the states that courts have interpreted to apply limitations equivalent to many of those in the Bill of Rights against the States.