Here's a fun thought experiment for you. If you dug a 1 mile cubic square hole. How many humans could you fit into it? The answer is not only all of us but about around an order of magnitude more on top. I'm not sure if this emphasizes how few humans there are, or how massive the Earth is. But it's the same point in both cases.

Some human activities can have an outsized impact, but the overwhelming majority of those activities remain necessary regardless of where people live, and some will have an greater impact with widespread urbanity since some things like energy/food/water can be relatively cleanly decentralized in rural settings, at least partially, but require complete centralization in urban settings.