Actually Howe's books, and others, are even earlier (The Musician's Companion 1840)and were a reaction to the expense of individual sheet music. In fact, these collections go back into the 17th C and were used by dance masters, such as Playford, to teach various dances of the time as well as provide tunes for the many collections of lyrics compiled for public use (Caledonian Pocket Companion etc etc). There are way too many to mention here; various archives are full of them. They were learned and passed through the oral/aural tradition as well.

Regarding the tunes mentioned, please remember that people would often change or replace the names of tunes for various reasons- one would have to do an extensive analysis of the collections to say that these tunes did not exist previously.
See Planxty George Barbazon / The Isle of Skye/ Twa Bonny Maidens- all the same tune, some with additional parts.

best- J