I'm curious how people with much less knowledge than I for thousands of years survived.

The key is that their knowledge is better-suited to subsistence than yours is. You may know way more math, science, and history than they do, but that doesn't grow crops or find water.

The short answer is they dig wells. Almost anywhere on earth, if you dig deep enough, you'll hit water. Every city, town, and village had public wells. If it runs dry, you cap it off and dig another one.

Well-digging goes back millennia. And if you're an archaeologist, they're pretty fun to excavate. People dropped lots of things in wells that they weren't getting back. And at the very bottom are well-preserved vessels that were dropped in and sunk to the bottom. But even better for interesting finds are outhouse pits (called by different names depending on place and time). If your ivory pendant broke off and fell in there, you're not going in after it. A gift to the future.