When Adam delved and Eve span, Who was then the gentleman? From the beginning all men by nature were created alike, and our bondage or servitude came in by the unjust oppression of naughty men. For if God would have had any bondmen from the beginning, he would have appointed who should be bond, and who free. And therefore I exhort you to consider that now the time is come, appointed to us by God, in which ye may (if ye will) cast off the yoke of bondage, and recover liberty.

John Ball (priest), in a sermon during the 1381 Peasant's Revolt. Like fubarobfusco says elsewhere in the thread, there were probably similar memes behind other similar revolts, that were suppressed and didn't survive into recorded history. (This one did because of the huge "memetic fitness" of the rhyming question at the start; I read it many years ago, and remembered it well enough to Google it and find the source now.)

Also, like Desrtopa said until the 17th century, if not later, peasants revolts were about specific grievances rather than an abstract concept of inequality.

Prior to the Enlightenment and secularism, "the abstract concept of inequality" was described as a religious concept rather than a secular one; and was a common feature of medieval "heresies".

peasants revolts were about specific grievances rather than an abstract concept of inequality.

What exactly is the difference? I want equality, and I have a list of specific changes (grievances, if you prefer) that I think would create equality.

Giving the peasants what they wanted would have reduced inequality. I assume the peasants leaders were smart enough to notice that fact.

Peasant revolts were actually pretty rare.

For every revolt large enough to actually make it on to a list like that (about one every generation), how many smaller, historically unimportant defiant acts in favor of equality occurred. The fact that the local elite didn't keep detailed records doesn't mean they didn't happen.

In parallel, major slave revolts in continental North America also happened about once every generation (it's hard to compare to peasant revolts because the historical record is better). Surely that isn't evidence that the slave population didn't express (or desire to express) complaints about inequality when they weren't engaged in armed uprisings.