I learned this very well in a writing group I belonged to for a time. We'd all be given a theme (genre) and given five things we needed to incorporate into our story, and then we'd write for 5 minutes. Even with all those ingredients, every story was so markedly different from everyone else's it helped me to realize that my muse is unique to me.
I often tell my students, a singer sings. A writer writes. A painter paints. A composer composes. We do the art for arts sake, because it lights us up inside and therefore is meaningful. If someone buys what we produce, that's cool. We need to eat. But that's not why we do it. Added to that is the willingness to listen and learn from others on the path, and a humble knowledge that our skill set now is better than it was six months ago, whether or not it is yet recognized by the 'experts' or our 'success' in 'selling' our 'product' is spotty at best.
That's not being an imposter, it's being an artist on the path to being a better artist ~