Sure, it was very much an economic fear tied to slavery, more than it was a "black people are lesser people and should be slaves" (Even though, of course, that was the sentiment), but it was still only ever about slavery.
The big problem with history class doesn't come from a lack of facts about what happened, but a lack of discussion about
why things happen.
The civil war, like most wars, was economic. The south was in favor of slavery for economic reasons, and the north was against slavery for economic reasons. They're the same reasons modern Americans are against immigration. It's simple supply and demand. If corporations can import tens of millions of people from China and India to do everything, what happens to wages? They crash. Your wages drop, your work conditions suck, your health benefits are cut, you have no work pension, and you need to work more hours just to pay the rent. How do you compete against
free labor? It's impossible. The existence of slavery in the south depresses wages in the north, just as the existence of China drives down wages in America (all of our high paying manufacturing jobs went to China).
The current narrative is that the war was about freeing slaves for humanitarian reasons. It's amazing that anyone actually believes this. We see disgusting working conditions in many countries around the world, but we do absolutely nothing to improve those conditions. We won't do as much as put an import tax on products coming from countries with poor working conditions, but we'll kill almost a million American soldiers to improve the lives of some Africans in the south? How could anyone possibly believe this?