Do I literally just click the cookie? Is that really all there is too it?
No. At first yes, but then you start buying things that generate cookies, from cursors to antimatter condensers. You can get upgrades to make these buildings better and to do other stuff. There are also achievements, for things such as cookies baked, buildings owned, etc. Then there's the Grandmapocalypse... It's scary how much time I've had it open.
Well, I guess I can welcome you to THE CLUB :) And no, that's not all: After a couple of minutes you can buy upgrades, which will generate cookies for you. After an hour or so, clicking itself is basically obsolete, because the cps (cookies per second) by your upgrades will be much higher than the ones you get from clicking. And then the hunt for upgrades and achievements is on!