I don't understand the superdeterminism idea. Wasn’t that already the classical/Newtonian view - that everything was predetermined, a universe of billiard balls following their destiny exactly?

Newtonian is just plain determinism. One thing causes another, but does not imply things are fixed in any particular way.

Superdeterminism implies that things are fixed in advance in such a way that the things we "choose" to measure always looks as if there are no local hidden variables (e.g. Bell's inequality) even though there are.