We're starting at the beginning here. The plow, developed in various places around the world about 10,000 years ago, is why humans have settlements. Before this, in the Paleolithic Age, humans traveled around as hunter-gatherers, finding what food they could. The plow made growing, and thus controlling, food supplies easier. Humans began to settle in places that became the cities, civilizations and cultures that we still have today. Everything you know about your history and culture more or less got its start here. We of course have no idea who, or more likely, which culture, developed the plow first due to its age. We do know that the adaptation from hunter-gatherer to farmer was pretty much a worldwide one, so we could attribute this to humanity at large.