Herzl’s zionism is simply a belief that Jewish people should buy land and live in their ancestral homeland.
He wasn’t orthodox, didn’t believe God promised anything to anyone, didn’t speak Hebrew, but after the Dreyfuss affair (usual racist fake accusation BS) started to petition Rothschild (he was denied) and then other wealthier Jewish people with more success to start buying sand dunes and swamplands for Jewish families to return to Israel.
Herzl is definitely worth either reading or just studying for HN, the books are short and to the point, they dispel a lot of myths one gets from the media, and starting a country is a fairly ambitious project worth studying for any founder.