> *Did we really know what “5” was then? What is five-ness really? Perhaps fiven...

> Did we really know what “5” was then? What is five-ness really? Perhaps fiveness is a set within a set within a set…

The reason it seems mushy is because there are two related concepts at play: a numeral vs. a number.

A numeral is the symbol: 5 in Arabic numerals in Latin script or ٥ in Arabic script; V in Roman numerals etc.

A number is the quantity, the amount being expressed: five (English), ḫamsa (Arabic), cinq (French) etc.