Yeah if you have been only coding for about a month definitely start with something very simple like an idle clicker. I am actually doing something very similar for this game jam lol if you want to tell me more about the game you want to originally make on your own maybe we can simplify it to make it possible for the game jam or even if not, maybe I can give you pointers for the future so you can do it better later. Otherwise the clicker is of course a good entry since you basically just need buttons, a few graphics and the game logic (like what the upgrades do and how much money the player gets etc.) is very straight forward.