Both writing and rewriting are necessary for most authors — I can’t think of any authors that haven’t gone back and rewritten their work — but of the two, writing is so far a lot more fun than rewriting.
Writing, you’re creating. You’re weaving threads together and the tapestry is taking shape.
Rewriting, you’re cutting out portions of what you’ve created. You’re double-checking the threads, cutting some, changing some to connect to different places, in some cases tossing a whole section in favor of something completely new.
There is some writing involved in rewriting, but it’s relatively limited. It’s mostly tweaking a word or a sentence here and there. Occasionally, as I said above, you’re writing new sections, but that’s pretty rare, at least in my limited experience.
Does that mean I was a bad writer, that I have to chop out whole sections and bring in something new? Will it go away as I gain in skill? I don’t know, but I guess I’ll find out.