I agree with the others. In a sense Josh’s course is designed as a good blend of lesson and things that most people will find fun, so it kind of fits all the roles here. It’s not necessary to go outside of that, but… I think it’s also important do things you personally enjoy. If you are interested in anything in the songs section of the site…
Yes, his list even has selection to sort them out. If I recall correctly, the video version of this list is roughly ordered as well.
There is also a section on the forum dedicated to this, check out the category “50 songs challenge”. Thread here. The song threads have youtube and spotify links as well as a lot of helpful comments and advice.
Do I have to be at a certain skill level with my bass playing to participate?
No. We started with the easier songs. If it takes you longer to learn a song, don’t be shy to post your recordings or questions whenever you feel ready. Imperfections and mistakes are very welcome and part of the process!