> a machine that can generate a poem or illustration depicting [CHARACTER_X] in [PLACE_Y] doing [ACTIVITY_Z] in [STYLE_S] without being creative

Your example disproves itself; that's a madlib. It's not creative, it's just rolling the dice and filling in the blanks. Complex die and complex blanks are a difference of degree only, not creativity.

It's not filling in the blanks that's impressive, it's meaningfully combining them all into an objectively unique narrative, building upon those blanks at length.

Definitions are always up for debate on instrumental grounds, but I'm dubious of any definition of "creative" that excludes truly unique yet meaningful artifacts. The only thing past that is ineffable stuff, which is inherently not very helpful for scientific discussion.