JimJim, you are correct that the central motivation of the Union was not to “free the slaves.” That doesn’t mean that the South’s motivations for secession were not to guarantee the institution of slavery. It was. Their articles of secession prove it. In other words, the central motivation for the Union was to maintain federal control over the states, but the central motivation for the Confederacy was to permanently enshrine slavery. Those two things can be true at the same time.
I grew up in the south, and was taught all of those same talking points in school, and believed them for years. “This is not a defense of slavery BUT…” As Mindysan has pointed out, all of them reduce down to slavery. I am especially ashamed to have been snowed by the industrial vs agrarian argument, as if that does not persist today.