If you are not remarkable in style and content, downloaders will graze upon you momentarily then move on. I think.
Sometimes someone comes up with the perfect thing for the time. EL James did that with 50 Shades of Grey. Rowling did it with Harry Potter. Who started the vampire craze was it Twilight or Anne Rice? They tap into something no one knew they wanted and are wildly successful.
You can't plan for that. You can try but I'm not aware of anyone who did this mechanically. These people wrote what they wanted and then the audience showed up.
Another way you can set yourself apart from the rest is by being talented.
We can't all be remarkably talented.
We can be skilled but that's work. It takes time. It also takes having the kind of mind that can conceive of improving and growing. Some people don't have that ability or thought process. They can be told how to improve but their minds can't work that out.
So now that we have millions of books available, how do we set ourselves apart from the masses?
What do we have to offer that readers might want. Some people want to read the same book over and over again but with slightly different characters and situations. Other people might call this predictable. The flip side would be to call it comforting.
Find out what you can do then do that to the best of your ability. Try to determine what your weaknesses are and strengthen them.
This could be called branding yourself. If a reader wants to read a comforting book that isn't challenging, do that. Be the person who becomes known for that. Promo that.
If you're going to write about quirky characters in unpredictable situations, be that. Be the go-to-guy for that.
Figure out where you heart is and be that.