structure of everyday life by braudel would give you lots of ideas how commodities production was close to impossible in myriads of ways: energy, population density, logistics, food production efficiency, on all fronts it was fucked in important ways

Unless you're going to reject anything that isn't orthodox marxist out of hand, I'd suggest you read John Haldon's "The State and the Tributary Mode of Production".

why they lacked the ability to produce proletariat on a scale required for socialist thought

I like the question, just a minor point: hidden in your question is the assumption, that those societies didn't produce socialist thought. That's not necessarily true. Remember, that we rely on the transmission of sources. The ruling classes mostly determine, which ideas are written down, published, distributed, translated(eg in the case of Aristoteles "Metaphysics" from Greek to Syriac), copied, translated again (eg from Syriac to Arabic), copied again and then copied a few more times while older copies decay and fall apart and finally translated some more (eg from Arabic to Latin and finally into English). At each of those moments, ideas got filtered and it always were the progressive ones, that were targeted and lost.

Slaves in ancient societies and peasants in medieval times might have had all kinds of brilliant dialectical insights, that just never reached us. We rely almost completely on the ideas of slave holders, oppressors, opportunists and exploiters to learn about the history of human thought.

Age of Empires II game manual

Socialism: Utopian and Scientific by Engels touches on it briefly.