The great Scott Adams (of Dilbert fame) said, "Creativity is allowing yourself to make mistakes. Art is knowing which ones to keep."
Mistakes, as we all know, are just a part of the creative process. Few (if any) writers are able to sit down and write out a novel in a single go, without a mistake, typo, plot hole, or error in their writing. Writing is very much trial and error process. Each time we sit down to write, we learn a bit more about creating. We improve our writing skills, ideas, and creativity over the course of a lifetime, not from one day to the next. Mistakes help us to learn, grow, and do better the next time.
But which mistakes aren't actually bad? Which are the ones that will make you better in the long run? It's impossible to know before you make them or have them corrected, which is why they are such a vital part of the learning process.
Let me give you an example:
In writing Book 3 of The Last Bucelarii series, I made some pretty big mistakes! To name a few: the Hunter did a number of things totally out of character for him, the story spent way too much time in the second act, and there was no payout for vital plot points. All pretty serious flaws, right?
Well, these mistakes have helped me immensely! Someone whose input I respect pointed out these problems, and proceeded to give me a crash course on the basics of proper storytelling. By the time I finished the lesson, I knew A LOT more about how to structure a novel properly, how to ensure that all the plot points pay off satisfactorily, and more. The mistake turned into a learning opportunity, which will turn into improvement and growth in my craft.
I'd rather not make the same mistakes again, but part of being creative is, as Scott Adams said, allowing myself to make those mistakes. As I continue to improve in my craft, I will avoid those mistakes and go on to making different ones. Those will help me learn and grow even more, taking me further down the path to being a true artist.
Make mistakes and learn from them. Use them, and you'll be a much better artist for it!