I've dabbled in multiple game engines, and have gotten fairly decent at Godot.  I'm even planning on releasing a game on Steam with Godot 4.4 as the engine. RPG Maker is new to me though. I ended up getting the Humble Bundle with MV in it, and decided to use that.

As for learning, YouTube is a treasure trove. SomeRanDev has an excellent beginning series, and I liked some of the specific of TheOdie's playlist, especially the cutscene one. Both of these are over 8 years old, and still pretty quality.  I'm about to start with this playlist from Ink Ribbon and while it's for "MZ", it seems pretty similar to MV.

I've got an idea for the GameJam, and I think it's achievable in RMMV, but I worry I may be too ambitious.  My plan is to prototype with built-in assets, and hopefully customize it. Though some of the things I want to include will need custom things from the beginning. Maybe it'll just be stick figures :)