Disregarding the (common!) assumption that AGI will consist of one monolithic LLM instead of dozens of specialized ones, I think your comment fails to invoke an accurate, consistent picture of creativity/"truly new" cognition.
To borrow Chomsky's framework: what makes humans unique and special is our ability to produce an infinite range of outputs that nonetheless conform to a set of linguistic rules. When viewed in this light, human creativity necessarily depends on the "linguistic rules" part of that; without a framework of meaning to work within, we would just be generating entropy, not meaningful expressions.
Obviously this applies most directly to external language, but I hope it's clear how it indirectly applies to internal cognition and--as we're discussing here--visual art.
TL;DR: LLMs are definitely creative, otherwise they wouldn't be able to produce semantically-meaningful, context-appropriate language in the first place. For a more empirical argument, just ask yourself how a machine that can generate a poem or illustration depicting [CHARACTER_X] in [PLACE_Y] doing [ACTIVITY_Z] in [STYLE_S] without being creative!
[1] Covered in the famous Chomsky v. Foucault debate, for the curious: https://www.youtube.com/watch?v=3wfNl2L0Gf8