Usign Site Builder features instead of default item_list.tpl
Using Jamroom
Seams like your kind of mixing 2 things, Site Builder and your module Lessons.
When creating a module one of the things that a module does is to have a default display page for all of its stuff.
Eg, the gallery module decides to display its stuff like this:
http://demo.jamroom.net/jrNova/gallery
The reason that stuff is formatted in the way it is is because the modules index.tpl file found at:
/modules/jrGallery/index.tpl
chooses to display it like that. So its the MODULE that says how the modules stuff should be formatted. There are no restrictions on it.
What you seam to want to do is to not provide a default index.tpl system in the module, but rather leave that page's formatting to another group of modules, the Site Builder system.
Its a bit un-expected.
If you really want to do it this way, I would suggest adding site builder setup to the modules index.tpl page.
"Making a skin site builder ready"
https://www.jamroom.net/site-builder/documentation/development/2349/making-a-skin-site-builder-ready
and add:
{jrPanel_display name="lesson"}Remember though that Site Builder doesn't work on profiles, its for building the top level content.
).