Screenwriting : This is likely a strange question, but by Brian Smith

I often have ideas that, on the surface, might be better suited to be written as books or short stories. But I really want to learn and practice screenwriting, so I have a hard time deciding if an idea is suited to a screenplay or not, I suppose any idea can be a screenplay, it is just a different medium for telling the story. Did anyone here start by writing long form fiction and transition to screenwriting? I'm just curious. I tend to overthink pretty much everything in my life, especially something like this where I have zero real experience. I can write and talk about software all day, as that is what I do, but this seems so damn scary just to get started. Fear of failure? Maybe, likely.