Plus, pre-modern age agricultural revolution, no created fertilizer, no pesticides, poor storage (no refrigeration, limited preserves, pest control), and no for

Plus, pre-modern age agricultural revolution, no created fertilizer, no pesticides, poor storage (no refrigeration, limited preserves, pest control), and no forced irrigation. So a drought, cicadas, pest explosion, shorter growing season, fungus/etc, wildfires, on and on, would immediately lend to famine, and perhaps war. Lots of additional people die during famine, fighting each other for scraps.