It was not solely about slavery.
That's true. Only for the South was it about the preservation of Slavery, for the North is was about keeping the South in the Union.
100% wrong.
Nope. It is accurate. The preservation of the institution was the main objective of secession.
The Reasons for Secession
1) Each declaration makes the defense of slavery a clear objective. .
Mississippi
Our position is thoroughly identified with the institution of slavery-- the greatest material interest of the world. Its labor supplies the product which constitutes by far the largest and most important portions of commerce of the earth… These products have become necessities of the world, and a blow at slavery is a blow at commerce and civilization.
Texas
The servitude of the African race, as existing in these States, is mutually beneficial to both bond and free, and is abundantly authorized and justified by the experience of mankind, and the revealed will of the Almighty Creator, as recognized by all Christian nations.
South Carolina
Those [Union] States have assumed the right of deciding upon the propriety of our domestic institutions; and have denied the rights of property established in fifteen of the States and recognized by the Constitution; they have denounced as sinful the institution of slavery
Georgia
That reason was [the North's] fixed purpose to limit, restrain, and finally abolish slavery in the States where it exists
Nice try, but you took your quotes out of context and failed to include this:
"The scholars immediately disagreed over the causes of the war and disagreement persists today. Many maintain that the primary cause of the war was the Southern states’ desire to preserve the institution of slavery. Others minimize slavery and point to other factors, such as taxation or the principle of States' Rights.
In 2011, at the outset of the sesquicentennial, a
Pew Research Center poll found that Americans were significantly divided on the issue, with 48% saying the war was "mainly about states' rights," 38% saying the war was "mainly about slavery," with the remainder answering "both equally" or "neither/don't know."