Again, you forget that every state was a slave state in 1780. There were agitators who wanted to end slavery, even in southern states, but none had actually achieved it when the constitution was signed.
The split of House and Senate was actually based on geography, as in which states had no defined western boarders.
The Founders called them small states and large states. The house was meant to appease large states, Which included New York and Pennsylvania.
The small states, got the Senate. Several of the small states had higher populations when the constitution was signed, but they knew it would shift out of their favor given enough time.
The line that the House was meant to appease Slave states is true only because New York and Pennsylvania were slave states at the time.
The 3/5ths compromise was thrown in to address this, but it isn’t the red herring you think it was.
The electoral college was then added again, because it took months to get from one end of the country to the other, and there was a distinct chance that the winner of an election would be dead by the time the Georgia electors got to Washington in order to officially cast the vote. That’s it. That’s the full reason it exists.
The presidential election was in the fall, and the certification was in the spring. All because there were no roads up and down the East Coast. No rail lines, no anything.
You could take a ship, but there was a distinct risk of dying at sea.
