Civil War cannons, like any muzzle-loader, will fire pretty much anything that fits down the barrel. They had a wide variety of rounds available. A solid cannonball isn’t going to explode and send things flying. If it his a human body it’s going to obliterate the part of the body it goes through, but it won’t send nearby people flying.
An explosive shell definitely will though. Here is a video of a Civil War cannon firing live explosive rounds at a modern Armored Personnel Carrier. That should give you an idea of the destructive power of a Civil War cannon. It should also give you an idea of its accuracy, or rather the lack thereof.
They also had mortars, which were short stubby cannons aimed up at roughly a 45 degree angle.
Mortars do this:
