@Art
The kickstart "hand" image is definitely in there but is most likely compressed. Looking at the picture it would be a good candidate for run-length encoding and also may be coded in a lower resolution than even 320x200 (e.g. just output the same colour for two pixels instead of one). Most of the screen itself is likely to just be a background colour that doesn't require a bitmap. The bitmap itself is centred where the pic is.
It isn't compressed in the V1.3 ROM image, but I think it is in the 8K bootstrap.
In the V1.3 image it is split into tiles all over the place.
It looks as if deliberately making it difficult to change.
It is also more than one bitmap.
I suspect up to four layers for some parts of it, but at least two.
The part where is says "Amiga" for example, is at least two layers
(maybe for some antialiasing?),
One layer of the "1" in "1.3" (for the Workbench requester)
is all on it's own, and so is one layer of the "bench", and one layer of the "Work".
I'm willing to bet this image has never been customised.
The actual hand and disk might be drawn the way you say.