Hello,
Your program is executing exactly the way you coded it. After the the first draw() loop (which has rectangles) the next loop falls through the while loop (10 is not < 10) and the canvas is cleared for each draw() cycle that follows.
I added a noLoop() to end of setup() so draw() only loops once and you can see output.
I also added some println() statements.
First cycle (frame) of draw():
After that background() clears canvas and it is grey.
Try initializing variables at start of draw before the while loop.
:)