At the beginning, she wore a canvas. She's always described her career as a canvas and how she can morph herself into whoever she wants to be. She's into the idea of shape-shifting. The performance started out as a blank canvas and throughout it she morphed into the different looks she's worn over the years.
She wasn't trying to say "hey look at me and how impressive my career is". She was basically trying to remind us that she will always start as a blank canvas, in a sense, with each new era.
The performance was incredible. Best dancing she's done in a while.