You are all over the place and I choose to address your scattershot approach one issue at a time. I'll start here:

"Article One, Section Nine, Clause One was directed AGAINST slavery, proposing the possibility of eliminating the importation of slaves after twenty years. Its adoption was a concession on the part of the slave states. You suggested that it somehow advanced the interests of the slave states."

You charitably describe the twenty year prohibition as as step toward the "possibility" of eliminating slavery. When the time came, there was no such proposal to eliminate slavery presented to Congress. Instead, an Act was passed in early 1807 to ensure the International Slave Trade was prohibited on the first day possible, January 1, 1808. Jefferson had flowery words.

"I congratulate you, fellow-citizens, on the approach of the period at which you may interpose your authority constitutionally, to withdraw the citizens of the United States from all further participation in those violations of human rights which have been so long continued on the unoffending inhabitants of Africa, and which the morality, the reputation, and the best interests of our country, have long been eager to proscribe."

but it is his actions that tell the story. The reason for eliminating the International Slave Trade but making no attempt to address the domestic slave trade was the desire to increase demand for domestic slaves, enriching in particular slaveowners in Virginia (like Jefferson who owned over 600 slaves in his lifetime making him one of the largest owner of slaves in the nation's history) and Maryland. Both states had excess slaves due to the deterioration of the tobacco marketplace because of poor rotation policies and soil management. Virginia was the primary beneficiary of this change (South Carolina was the big loser) but got the Act passed, partially due to their excessive influence related to the way Congressional seats were allocated, related to the three-fifths clause. After the elimination of the international slave trade, slavery existed another 50 years so it wasn't much of a first step was it? Next you'll want to tell me the Emancipation Proclamation was intended to eliminate slavery instead of an attempt to disrupt the South's economy and keep Britain and France from siding with the Confederacy. Rewriting history to make it sound better isn't becoming.