Slaves weren't citizens. They weren't even "people" They had the standing of pigs and chickens. So unless you think the 2 million pigs and 4 million chickens in Mississippi should have gotten representation in congress, you have to concede the argument.
So
you ARE arguing that they should have been given no standing at all. Would that have been better than not getting our Constitution at all? There is a reason it's called the 3/5ths compromise".
Actually i'd argue, they SHOULD have been citizens, counted 100% and given the right to vote.
But i'm TELLING you the law in effect at the time. They were not citizens, they were not people, and the 3/5ths were votes denied to slaves and GIVEN to their owners. Making it 1 man, 1.66 votes.