I'll need to check some references (I think Speiser addresses this), but my
off-hand recollection is that using the cardinal number "one" in an ordinal
sense ("first") when it's in the context of a list is known in other Semitic
languages. (Anyone have the Ugaritic handbook handy?)
Cf. English: "He's been on this email list since Day One" means "He's been on
this email list since the first day." It does not mean "He's been on this
emmail list since one day."