agreed - America went through a "mandolin mania" in ~1880s, and even in the 1900s and 1910s, the guitar was by no means an established instrument.
As a matter of fact, the "tenor guitar" was made for people who knew how to play the very popular four string banjo, but wanted to play a guitar without learning new chords.
Instruments were in a state of change, and the "harp" nomenclature (and styling) for a 12-string guitar was more a marketing flourish than a family lineage.
> the "tenor guitar"
Would that be a ukulele? Or is that something different yet?
Different lineage[1] as (partially) mentioned above; the ukulele evolved from small Portuguese instruments[2], and is tuned about 3 full steps higher.
[1]https://en.wikipedia.org/wiki/Tenor_guitar
[2]https://en.wikipedia.org/wiki/Ukulele#History