I believe you're confusing the Declaration of Causes with the actual Ordinances of Secession.
Slavery, Slavery, Slavery! Of course in the cold light of the morning after other states realized that telling the truth was, shall we say, messy and embarrassing. So they tried to avoid being honest. But too late, the truth was out. Messed everything up, too.
No, that four Confederate states did not secede due to slavery is simply fact. I understand that fact doesn't fit your narrative, but it doesn't change the fact.
As for the northern degrading itself, how?
By choosing to violate the Constitution.
The northern states werent engaging in slavery.
A little more study will enlighten you to the fact that this isn't a true statement. There were still slaves held in some Northern states.
As for the for the slave states that didn't secede, you are as aware as I am that those weren't the states that the South Carolina secessionists were complaining about.
You and I know both know the institution of slavery is intrinsically evil. So the northern states could not degrade themselves by declining to support it by returning escaped slaves. The southern states degraded themselves by demanding the return.
Or are you willing to argue that the southern states did not degrade themselves by the institution of slavery, that slavery is not intrinsically evil? If so, good luck with that.
“No bill of attainder, ex post facto law, or law denying or impairing the right of property in negro slaves shall be passed [by Congress]”