Dear @pete
I was curious too!
I De-actived & Deleted My Lay Theme
and re-installed it from the basic original Folder - Lay.zip,
My content was still there waiting,
[image: 1598465365302-screen-shot-2020-08-26-at-8.03.25-pm-resized.png]
[image: 1598465372503-screen-shot-2020-08-26-at-8.03.32-pm-resized.png]
[image: 1598465378997-screen-shot-2020-08-26-at-8.03.39-pm-resized.png]
"Projects" now being "Posts" -
And then when re-installed My content was still there,
[image: 1598465518765-screen-shot-2020-08-26-at-8.11.45-pm-resized.png]
I would always advise backing up the folders through your Webhost as a safety precaution, be careful :)
Hope this helps
Best
Richard