Just this week i read an article in a 1986 Byte magazine which included a comparison of the Amiga and Macintosh graphic privatives. The Amiga had color routines, but the Mac had circles, curves, rounded rectangles, and a few other desirable shapes that the Amiga lacked.
Except for the text, the Kickstart image is not a bitmap, it's the output of a vector drawing program using the built-in ROM routines. No curves, and that's what you get.
Edit: September, 1986, page 251.
(I couldn't find the specific intros with the funny graphic...)
I didn't do the color flood fill, and something isn't quite right, but it's recognizable.
but it just gets the color of the final path, and I don't know why.
You can have some fun with causing it to corrupt https://www.youtube.com/watch?v=7VcbhDbCY7Q
The Amiga used a standard 320x200 pixel mode  for it's boot screen. On a normal 4:3 CRT this mean the pixels are non-square. Since CRTs are analog, it doesn't really matter to the monitor, but if you just look at the digital bits without stretching them it looks a little flat.
Source: lived through those times...
Strictly speaking, I don't think square pixels were a characteristic of the monitor. If you looked closely there were little dots on a shadow mask monitor considerably smaller than the average pixel, or horizontal gaps between the wires on a trinitron.