Collaborative unmanned systems have emerged to meet our society's wide-ranging grand challenges, with their advantages including high performance, efficiency, flexibility, and inherent resilience. Increasing levels of group/team autonomy have also been achieved due to the embodiment of artificial intelligence (AI). However, the current networked unmanned systems still do not have sufficient human-level intelligence and human needs fulfillment for the challenging missions in our lives. We propose in this paper a vision of human-centric networked unmanned systems: Unmanned Intelligent Clusters (UnIC). Within this vision, distributed unmanned systems and humans are connected via knowledge to achieve cognition. This paper details UnIC's concept, sources of intelligence, and layered architecture, and review enabling technologies for achieving this vision. In addition to the technological aspects, the social acceptance is highlighted.