Everyone has their own process, but I think it’s fine to just start with a simple idea that’s not yet a game, jump in, and experiment around, especially if you’re just starting out. I’m not an expert by any means, but I managed to release a small game of my own recently, and all I had at the start was a test where I could knock over a box by throwing a ball. Everything else that eventually became the game were ideas that I had later while playing around and showing it to other people.

This was my first game jam ever and I’m happy to say mine is one of the thousands of Godot games this year. The web export in 4.3 worked without any issues for me.