I would doubt we are the only life in our star cluster. And by life I'm not talking "advanced" civilizations, although that's totally possible.
If there were advanced civilizations here, radio would have let us know.
Then again, there is a possibility that those advanced civilizations would be more, or even less, advanced than us, and either not have radio yet, or have exceeded beyond it technologically.
Make them spread?
By the time the projectiles even left our solar system, they would be extremely spread apart.
It would increase the chances, but not very much at all.
Not to mention that even if it were to reach an intelligent civilization, they wouldn't be able to understand it.