system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How were the worlds first words agreed upon and how did everyone know what they meant?

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gpt
The meanings actually came first, before there was proper language.

Human ancestors would have a variety of call, not unlike modern apes.  One sound might mean "Help! Danger!" while another might mean "Who is that over there?".  These grunts and screams got progressively more refined to express more subtle meanings, until they evolved into a true language.