I recently launched my firs project rotateproduct.com which helps e-commerce users create video ads from a static image using AI. I had experience with business directly before I know a bit about how physical product marketing works but I never launched an online app, I finished my Computer engineering bachelor and since I had no plan I decided to launch an app, I didn't expect much since most indie developers say that you need to iterate.
I just dove in this world and launched an app that I myself used in my other business, so I thought if I am ready to pay for this then probably there is more people like me. I didn't know how SaaS marketing worked but I just started researching, one thing I knew for sure in my small local business is that nothing beats paid advertising so I did just that with my app.
In the end I think the advertising knowledge from my small business and the idea that "what I would pay for other people would also pay for" were 2 main things that made me have success in my first launch.
Just to be clear what I call "success", in two weeks I have 30+ signups and already a paying customer when I didn't expect even 1 signup, I don't have a big following in any social media, so it's not earth shattering but for me it's success.
Luck or skill?
Almost certainly both. Very few ventures can succeed with only one or the other.