Many here may be too young to remember but depicting black people as apes and monkeys and subhuman was a thing back in the 1800's and before the civil rights movement and there was a Supreme Court case declaring that Negroes were only 3/5 human and there fore subjected to being owned by the White man. (Dred Scott).
While there is a whole lot wrong with Dred Scott v. Sandford, this isn't what happened in the case. They never declared that Negros "were only 3/5" human. First, the whole 3/5 thing was in the Constitution itself, but even then the claim that "Negros were only 3/5 human" is misrepresenting it. What the Constitution said was:
"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".
The only people who weren't "free persons, including those bound to service for a term of years" or "Indians not taxed" are slaves. So for the purpose of determining the population of a state, it meant that you'd take the slave population, multiply it by 3/5, and add that. This was done as a compromise between factions who wanted to count slaves fully in the population and those who didn't want them counted at all, so the compromise was to count 3/5 of them, and is called the 3/5 Compromise.
So this 3/5 was in reference only to numerically determining the population and thus did not mean anyone was actually "3/5 human" and more importantly, did not apply to all blacks, only the slaves. Thus this did not say that "Negros were only 3/5 human".
This brings us to what Dred Scott
actually said. In the first place, the case wasn't at all about whether blacks
could be owned by the White man--slavery was longstanding practice and while there was a lot of controversy over whether it
should be legal, there wasn't much controversy over whether it
was legal. The fact slavery was constitutional was not in dispute.
What Dred Scott
did decide was the following two things:
1) People of African descent were forbidden by the Constitution to become citizens of the United States
2) The federal government was not allowed to ban slavery in the territories (i.e. areas part of the United States but not a formal state)
These conclusions and their reasoning have gotten a lot of criticism, back then and now, and Dred Scott is generally considered one of the worst decisions the Supreme Court ever issued. Regardless, that was what Dred Scott decided. It wasn't about whether blacks were 3/5 of a person (I don't think the opinion even mentions the 3/5 compromise), whether they could be owned (they obviously could be), but whether they could be citizens and the question of territories.