Just a few thoughts for the conversation:

Initially, those who owned many horses were able to have performed the greatest amount of work, thus generating the most wealth. Horses were the needed extra muscle over many who did not have horses. To a degree, horses equaled power.

Was it the industrial revolution with the introduction of steam power, heavy machinery, then the discoveries of oil and gas that ultimately freed the majority of people from physical slavery? Did they become less useful overall because they couldn't perform the same work as the machines? It must have lead to a race to gather the most, most powerful machines.

Skipping ahead into the future we now have AI system's power, where the powerful can easily control more than ever with the least amount of effort. Yes, I'd venture we are all slaves now, more so than ever in history (Spiritually, mentally and financially for sure).

If we shut down the fossil fuel industries, will this eventually lead to a return to abject slavery like in earlier times?

Will human nature ever change?