Wouldn't we all love to create great things that our successors will discuss for centuries to come? For something to make such an impact, it has to be pretty amazing.
However, the path to greatness is long and rocky. Many of us don't get started at all because they have too high expectations for themselves. They expect to create incredible work from the get-go. When it doesn't happen, and their work turns out to be crap, they give up. To soon.
But everyone who has ever achieved greatness has started just like that. With really crappy first drafts and failures after failures.
Supposedly, it takes around 10 000 hours to master a craft truly. I've also heard that musicians and other artists perform and practice for ten years before they produce their best work. Those ten years are often referred to as the "years of silence" because there is no applause or recognition. Yet.
You have to give yourself permission to produce junk at first. That's what's going to happen. Only if you persist and put in the work regularly, you'll eventually live up to your own expectations and produce the work you can be proud of. And maybe, you can even achieve greatness.