Nearly everyone who runs seriously "fails" if we define failure as coming up short of what you hoped would happen. And if you move beyond running and look at life in general you'll see that whatever you do there are almost certainly thousands and perhaps millions of people who are better than you at anything you do.
Run on a golf course and look at the golfers. Do you think they're there because they think a little more practice will allow them to beat Tiger Woods? They're there because they enjoy playing golf. Sure, some of them will be frustrated because no matter how hard they try they can't beat their brother-in-law who they find sort of obnoxious anyway, but golfers, bowlers, tennis and softball players are all pretty aware of their place on the food chain and just there because they like what they do.
One of my heroes in the sport is Ron Hill who hasn't missed a day's run since December, 1964 and at 74 is still running each day and racing regularly. His times for 5 and 10 km now are just a shade faster than what he used to do for 10 and 20 km and he only manages to beat a handful of people when he races. But he doesn't care. He loves the sport and once asked why someone should give up something they love just because they aren't as good at it as they once were.
Other than you, no one really cares how fast or slow you are. Decide if you're running because you enjoy the sport or if it's because you're trying to impress someone. If it's the latter and you aren't succeeding, maybe it's time to move on. But if you enjoy the sport stick around and like a golfer or bowler be glad you have a chance to do it.