As social robots become increasingly integrated into care and companionship settings, understanding how older adults perceive the humanness of robots is critical to promoting acceptance and effective adoption. Drawing on the dual model of humanness, which distinguishes between human nature and human uniqueness, this study investigated how older Chinese adults attribute these dimensions to social robots and how such perceptions influence their attitudes and intentions to use. A cross-sectional questionnaire survey was conducted with 412 community-dwelling adults aged 50 and above in China. Participants were randomly assigned to view one of 12 robot stimuli varying in anthropomorphic features. Perceptions of humanness, attitudes toward robots, and intention to use were measured. Results revealed that participants attributed both human nature and human uniqueness at significantly above-midpoint levels, suggesting a general openness to ascribe humanness traits to robots. Android and humanoid robots were rated higher on both dimensions and evoked greater intention to use. Multiple regression analyses controlling for age, gender, and education showed that both human nature and human uniqueness significantly predicted usage intention. Notably, human nature was associated with more favorable individual attitudes and fewer societal concerns, whereas human uniqueness influenced intention but not attitudes. These findings highlight the distinct functional roles of human nature and human uniqueness. Practically, it underscores the importance of designing robots with emotional and moral cues to enhance acceptance among older adults.