(Mt Greek testament is packed up. Does Paul use aner or anthropos? The former means man as in guy, the latter man as in human.)
Aren't you EVER going to unpack??? ;o)
In Romans 5:12, Paul uses the word anthropos which can mean in the general sense all mankind, but he specifically used the word before that, heis, which means the numeral "one". The context, then, signified one man (Adam) just as the next use of the word is preceded by pas which denotes all, i.e., all men, all have sinned.