That is just as incorrect as saying the US Senate was intended to dehumanize black slaves.

Both the Electoral  College and the US Senate were intended to protect small states (initially mostly in the relatively slave-free North) from domination by the more populated or largely unsettled states (of initially the mid-Atlantic and South).

The 3/5 rule was a result of the enslaved status of blacks.... not a cause if that enslavement.

Ironically, in the Constitutional Convention, it was the slave masters of the southern states that wanted slaves counted as full persons vrs the northern state representatives who wanted slaves counted not at all because they were not free men eligible to actually vote.

Slavery was a terrible practice. But it had nothing to do with the creation of an Electoral College.