1) You don't think we humans are necessarily descended from Adam and Eve. But you believe that African blacks are all descended from a cursed son of Adam named Cain--and that they were denied the priesthood only because of this bloodline.
Or they followed after him.
2) You don't believe in a global flood, but you believe the African people are all descended through the loins of Ham, who was on Noah's boat carrying the curse of Cain in a local flood in the Middle East.
Or their population is "leavened" by the descendants of Ham and/or the believers in that attempt to imitate the Priesthood.
3) African blacks carried this curse (from their ancestor, Cain), through all times and places, until 1978 when the president of the Church released them from it and allowed them to finally have the priesthood.
I believe the Church did the best it could with the knowledge it had to apply Abraham 1. I believe it was probably good enough to accomplish the goal (I can only speculate as to what that was). I have never said they did it perfectly. The ban itself is not a problem because it is in the scriptures and doctrine.
4) The second Article of Faith says: "We believe that men will be punished for their own sins, and not for Adam's transgression." However, Cain's descendants had to be punished for his transgression for thousands of years. And Cain's descendants are only African blacks or those with that bloodline.
I've already differentiated between being punished for one's own sins and the consequences one's choices can have on an entire group of people.
Additionally, (except for the local flood) you believe these are all LDS doctrine (or at the very least are compatible).
As you can see, that is not the case.