I'm very curious where you got these ideas of what was and was not "lost", because they're mostly wrong. Sparta was not a high point of women's rights nor economics, but we have flairs who are more able to explain that than I am. As for the Middle Ages, none of the ancient ideas you list (that were actually present in the ancient world) were lost even when the texts that first record them became unavailable to Latin readers.

For example, medieval people knew the Earth was round. u/qed1 has this answer on medieval belief that the Earth is round, and some more from u/jschooltiger here.

They also knew what dialectics were, as although some parts of early medieval Europe lost direct access to Plato's writing his ideas were transmitted by writers they did have access to like Saint Augustine and Boethius. There are loads of medieval philosophical and political treatises written in the form of a dialectical discussion - Saint Anselm alone wrote many on various philosophical matters. Outside of prolific writers of dialectics like Anselm there is Dialogus de Scaccario, a dialogue on the English government under King Henry II that is one of our most valuable sources on medieval administration. There is the work of the 9th century philosopher John Scotus Eriugena - De Divisione Naturae - who viewed history itself as a dialectical enterprise leading him to sometimes be referred to as an early medieval Hegel. Many of the earliest texts on chivalry like Ramon Lull's Book of the Order of Chivalry and the early 13th century poem Poem of the Order of Chivalry take the form of dialogues. It's no exaggeration to say that dialectics were a cornerstone of medieval education and philosophy, and always had been.

Epistemology didn't go anywhere either, since considering the nature of knowledge is in many ways a prerequisite to doing any philosophy or theology at all. Anselm's first dialogues is De Veritate (On Truth), in which he discusses with a student various types of ways in which true knowledge is created and revealed.

It's also worth noting the existence of Islamic, Byzantine, and Jewish philosophers in the early Middle Ages who often did have direct access to classical Greek texts and the ideas therein and developed them further. These groups were often in contact with each other and with the philosophers and theologians of monastic and cathedral schools that dotted medieval Europe. You can read about their work and interactions in an answer by u/udreaudsurarea here.

It's not that any of the things you've brought up were dormant. They were certainly around. While it is true that we have more of it from 1200 onwards, it's also true that we have more of everything, because it's more recent so there's less time for stuff to have been lost. We know of some fantastic pre-1200 philosophers who did amazing work on the things you've brought up but only through letters and other works praising them. For example, the 11th century philosopher Bernard of Chartres is said to have done some groundbreaking epistemological work, but the only bit of it that survives is how he summed it up to his friend John of Salisbury, who then quoted Bernard in his own work. Oddly, despite surviving only as a quote, it's one of the few pieces of medieval epistemology that is known by millions of people, since it's the phrase "standing on the shoulders of giants".