Yes, the Spanish Civil War helped line up the adversaries for WWII. Along with the conflicts between the USSR & Japan, China & Japan, the Italian invasions of Albania & Ethiopia, the Winter War between Finland and the USSR, the fighting between the newly-created Poland and the fledgling USSR in the 1920s (even the brief intervention by the US in the Russian Civil War)...These helped line up the sides for WWI part II (aka WWII).
The books listed (at least at first glance) seem to be a pro-Republic (communist) lot; I’d recommend “The Last Crusade” by Warren Carroll for the other side of the story. It describes exactly what the left was doing that triggered the military revolt, and also what the left did in response to it - all whitewashed from history.
Nice, I just ordered “The Last Crusade” and you seem to be correct about the other 5 books all being slanted towards the left. So will start with yours first