Recent breakthroughs in AI-generated music open the door for new forms for co-creation and co-creativity. We present Artificial.fm, a proof-of-concept casual creator that blends AI-music generation, subjective ratings, and personalized recommendation for the creation and curation of AI-generated music. Listeners can rate emergent songs to steer the evolution of future music. They can also personalize their preferences to better navigate the possibility space. As a "slow creator" with many human stakeholders, Artificial.fm is an example of how casual creators can leverage human curation at scale to collectively navigate a possibility space. It also provides a case study to reflect on how ownership should be considered in these contexts. We report on the design and development of Artificial.fm, and provide a legal analysis on the ownership of artifacts generated on the platform.