Regarding your point #2: The counting of the slaves as 3/5 of a person was a strategy by the Northern Abolitionists to reduce the population of the slavery states so slavery states would have fewer members of congress.
As I'm sure you know, members of the House of Representatives are allocated by the population of the states, not the number of voters in a state.
Using that as an example of considering slaves as inferior is inaccurate, since slaves could not vote or influence the election of members of the House of Representatives. If the slave had been fully counted the slavery states would have had more representatives and thus more influence prior to the secession.
I am aware of the compromise reached on slaves being counted at a reduced population for congress. Once again the non slave states pushed through the idea that slaves weren’t true citizens and as such were not counted fully for representation in congress. Slaves were deemed inferior to citizens. And codified into the basic governing document of the country. At the request of the non slave states. Which now act sanctimonious about slavery, after all they did nothing to support slavery, except make it legal of course. Holier than thou Batman.