Thank you for reading.
To be honest, I wasn't sure if it was too long a read, but I wanted to explain where I am now and how I got to this point. Everyone's story will be different, with different backgrounds and hurdles they've overcome. If this post can help someone find a bit more confidence, or realise that we all start somewhere, then it was worth making the post.
I think, the first time anyone uploads their game and joins a jam there will always be doubts. I think the trick is to just do it anyway, yes you have doubts, but you won't move forwards unless you do it. That's what I did, that seems to be what you did, and I don't regret it.