This paper asks how human-AI co-creation in marketing can be made governable, measurable, and brand-safe. Specifically, it examines whether Artificial Collective Intentionality (ACI) can explain how a human-AI ensemble forms, sustains, and revises shared marketing goals under explicit constraints. The study focuses on three linked questions: how semiotic alignment supports audience fit and brand voice; how normative governance translates duties, permissions, and prohibitions into contestable rule-linked explanations; and how collective action enables commitments, delegation, repair, and consensus in campaign, launch, and crisis settings. The broader question is not whether generative AI can produce creative content faster, but whether marketing teams can use AI as an accountable collaborative partner without losing control over claim validity, compliance, or reputational risk