I also had the "I spent 23 minutes designing this scene in blender" impression of the ball, table, and disembodied hand. The table was made of light grey, the ball was made of light grey, and the hand was made of light grey

• What happens to the ball?

It slowly rolled toward the edge but stopped before falling to the ground. The path was somewhat eccentric because of the texture of the ball.

• What color was the ball?

Yellow

• What gender was the person that pushed the ball?

Male

• What did they look like?

Green and white track suit (why? IDK), mid 60's Italian, chubby

• What size is the ball? Like a marble, or a baseball, or a basketball, or something else?

It was one of those foam Nerf bullets, so about the size of a shooter marble

• What about the table, what shape was it? What is it made of?

It was that black IKEA table where the four metal legs screw into the corners. About 6ft by 3ft.

• And now the important question: Did you already know, or did you have to choose a color/gender/size, etc. after being asked these questions?

The entire scene sprung into my head at once after reading that someone interacted with the ball

Yeah, same with me. But I knew the ball was pushed and rolled to the edge of the table and then fell, so I feel like I got the most relevant bit.

Tbh I've never been good at visualising faces, recognising people I know, retracing a route I've taken etc. This just feels like one of those things I've never really been great at.

Do people really usually have a more vivid picture in their heads?

I can't speak for others, but I do if they're concepts I've encountered before. I have "default" visualizations of things that are changed if the description warrants it.