Where does that say that in the Amendment XIV re : slaves? You see that is why it will possibly get overturned.
Using another example, Amendment 2, the right to bear arms is enshrined in the Constitution - at the time the guns were muskets not semi-automatics.
You see how it works now. It is the wording that is important not the time.
Same reason that President Trump can’t run for a third term.
The time provides the context as to what the amendment is designed to achieve. Muskets is a terrible analogy because the amendment was designed to allow citizens to use weapons to defend themselves against invaders. It’s perfectly logical that as weapon tech progresses the weapons they use to defend their land keeps up.