Question: What's the purpose of drawing parts?

I was somehow able to keep up with almost every progress the game provided, like trigonometric, circles, etc… but this mission… I finished it by putting one digit at a time like a primitive ape would do. Did I have to figure out what’s going on inside of every drawing functions? Or at least the starting angles or what not? I even moved the centers of some shapes’ y positions from the initial marks manually, which I’m not so sure that was a intended level design. I feel stupid after this mission, it was WAY too hard. I hope somebody says it’s normal for anyone who’s playing it. Exactly what should I have learned from this mission?

perhaps its trying to teach you hwo to draw with code