Who was left out of the world's first democracy: slaves, women and foreigners?

In classical Athens, free adult men who were citizens held all the political power, and almost everyone else had none: women, foreign residents and slaves. Slavery was a widely accepted practice in ancient Greece. Its principal use was in agriculture, but slaves also worked in stone quarries and mines, as domestic servants and even as a public utility. Athens had the largest slave population, perhaps as many as 80,000, on average three or four per household. The majority of free Athenians appear to have owned at least one slave, and owning none was a clear sign of poverty.

Slaves were property. Aristotle's Politics called them "living tools" and "animate property". Their lives varied: the mine slaves of Laurion lived a particularly brutal existence, while public slaves, craftsmen and bankers enjoyed relative independence. Around 20,000 Athenian slaves ran away at the end of the Peloponnesian War, at the incitement of a Spartan garrison.

Another group, the metics, were residents who were citizens of another polis. Their status was like modern permanent residency, with indefinite residence but no political rights. One estimate puts the male metic population of Attica in 431 BC at about 25,000, roughly a third of the total.

Women were also left out. Women in classical Athens had no legal personhood and were assumed to be part of a household headed by the male kyrios, or master. Women in Athens were excluded from essentially all public life.

So the democracy was real, but it belonged to a minority. The people were not "everyone".