I think it is the triangle
The origin point for shape and form, in our universe that is
If we start from a single point, with nothing else, simply floating empty in the vacuum which cannot even be named with a color, then we have nothing except ourselves in with which to observe, measure and compare against. Cast ratios.
No yard stick to align against, no way to even tell if we are moving, if we are even a we or an I or a you
Upon the ocean, we could cast out a rope, and count how regularly the knots were fed out behind the ship, to gain some timing, like a comma.
But in space with nothing else, we would reach out our arm as a measuring device. We are the only thing, so we are the only measurement, the only ratio.
And so everything in our universe will be a direct ratio, proportional to, well, US!

So, we reach out and SPIN or to rotate, locomotion. We are not perfectly symmetrical so we do have spin!
It is measurable. It is known Khaleesi
So we built a point, now we need a second point so that we can build a line between them
We have a ratio, 1 "Us"
So we make a copy of the only thing we have ever know, again the greatest (and only, so far, as of just yet) thing ever, you guessed it, US!
2 Us'es are bussin
Fr Fr No Cap No Cap On Gawd On Gawd Get the papers Get the papers Jeeze you've got a big pussy Jeeze you've got a big pussy

So we now have multiple measurements and observations, ratios in with which to work and make comparisons.
Now there is a 1 Point ---a + line--- and 1 Point
2 points, with a line connecting them. All made of MUAH!
/dabs
Add a second line to build a circuit, or circle

But "bent" lines in our dimension of travel, at our plank level of time/build in our F/B, L/R, U/D movement means you go forward, then left, then forward, then left, then forward, than left...we are not high enough in the Plank build to see smooth movement at Plank level 32 or so

So triangle it is
3 points, three lines
First shape
First structure
Grats
Ding
GG EZ triangle