Agriculture
If you ask someone which is the most revolutionary invention in history, their responses might go from the Internet to the wheel. However, none of those things would’ve been possible without the simplest yet most crucial innovation in history: agriculture.

Without crops and animal domestication, our ancestors wouldn’t have been capable of building settled communities and, later, civilizations. Moreover, if ancient people hadn’t been well-fed, they wouldn’t have had time to develop world-changing ideas, right?