Contrary to the idea that nothing changed much in the premodern era, there were several instances of growth. Most notably, there was population growth from about 50 million in 1000BC to 900 million in 1800AD. Secondly (and the main cause of the former) was the expansion of farming lands, and the expansion of farmers at the expense of foragers. Third, agricultural production grew slowly, such as when crops from one area were introduced in a new area. The Arabs, following their conquests, brought several crops from India, including sugar. The Europeans exchanged old and new world species. Fourth, technology grew, albeit slowly and very unevenly. Fourth, cities grew. The total number of cities grew. In addition, the proportion of the world’s population living in cities grew slightly from about 1% in the early agrarian age to about 5% on the eve of the modern age. Fifthly, empires grew larger and more long-lived, suggesting that political organization grew more sophisticated.
For more on all this a good source is Eric Jones, “Extensive Growth in Premodern History” in Johan Goudsblom, Eric Jones and Stephen Mennel, The Course of Human History: Economic Growth, Social Process, and Civilization (Armonk NY: M.E. Sharpe, 1996).