I think more of us are in this boat than you realize. Medium is sort of a double-edged sword, in that you’re free to write just about anything, but there are certain unspoken expectations about what belongs here. Medium isn’t a blog, and it’s generally understood that articles should be both well-written and appealing to a fairly wide audience.
Every time I hit that “Publish” button, I wonder if my article is even suitable for Medium. That’s never stopped me from publishing, so I guess my judgment is either perfect or incredibly flawed.
And of course, as you pointed out, this place can be pretty intimidating. Ordinary folks like us are putting our work out there alongside Matt Bors, Craig Newmark, Rosemary Rodriguez, and many others. Even if we’re egotistical enough to think that our work is just as interesting as theirs, they still have a much larger audience than we do.
I haven’t been on Medium very long, but I wrote about my experiences here : https://medium.com/@ohgodscrewthis/why-am-i-here-35d85e091c2c#.8lxl9ypub