Republic confusion / First Order history. Post Starkiller attack, post TLJ resistance-killing, I'm really confused about the socio-political scene of the galaxy. I don't need PT levels of politico-senate scenes. I would just love a simple, straight-forward explanation along the lines of "The First Order formed in a corner of the galaxy where all the last remaining Empire forces stayed strong. Snoke stepped up to lead them, and rebranded them while the Republic slowly restored itself. The First Order grew, the Republic didn't want to get involved, Leia decided that was bull so she went to First Order controlled space to build a resistance. Now, with the Republic capital gone, and the First Order growing stronger, one final push has to be made to show the rest of the galaxy they need to be stopped.
What I never understood is, where was the Republic's army? Why was the FO fighting a small resistance movement instead of an army? Did the Republic, in the thirty years between trilogies, just never form one?