Hi
If you want to learn game jams are perfect indeed, but I do believe that you'll have more success finding the experience you're looking for in a real life jam. Getting thought a new skill while not actually in the same room seems real difficult to me.
Why not choose something real small in scope, like a frogger or minesweeper clone and trying to do it solo.
It sounds as If you have all the knowledge needed to get started and the internet is literally a treasure trove of information. You could also ask any specific questions about how to solve a particular problem here and I (as many others I imagine) will be happy to help out if able.
Bottom line: I think an online collabiration isn't well suited for the kind of learning experience you're after but don't let that stop you from making something on your own.
And whatever you do, FINALLY FINISH SOMETHING!