We are simply deformed cylinders, all of us.
Just take a cylinder, a hollow one, and you have a basic organism. You just need to stretch it the long way a bit. And make it narrower.
That space from one end to the other is just an intestinal tract. Food goes in one end, waste comes out the other. It’s a good, simple, durable design. The worm, earthworm and other kinds, is a working example.
Now, you can imagine how you get this doughnut (torus) from the cylinder up above, can’t you? Just fatten the walls a lot, and you’re done. If you add little bumps and squeezes to it, and stretch some of the bumps into limbs, arms and legs, you would have a simple humanoid shape. But it wouldn’t be too different from the original cylinder we started with, at least not from the topological point of view.
Just push, pinch, squeeze, and form the dough a bit until the center of the doughnut is stretched out enough to be the neck with a head on top of it, and you have a human. This topological diagram of the human GI tract makes my point… see how the intestine just runs straight through?
Now, just what was my point? Back to the mud…