He was always energetic and positive and he was a people person. People is a collective noun. When we talk about a specific group of people, we consider it as singular and therefore, no need to add s.
A people person is someone who is outgoing and has good communication skills. What is the plural of people person? 倾听人民呼声 汇聚人民智慧 下载“人民网+”客户端 给领导留言 扫码关注公众号 “领导留言板”客服邮箱:leader@people.cn