Do 男人 and 女人 have an unfavourable connotation?
男人 and 女人 are used when talking about the relationship between women and men or when talking about specific characteristics of 男人 or 女人. Without knowing your detailed context, my best guess would be that you use them to indicate a serious situation where the generic gender terms should be used, which are 男的 and 女的, or just 男 and 女.