You greatly overestimate the size of the solar system. Our solar system is a mere ~20 light hours in radius. We even have two man made objects out of the solar

You greatly overestimate the size of the solar system. Our solar system is a mere ~20 light hours in radius. We even have two man made objects out of the solar system (Voyager 1 and 2). In a century, our signals already made it past ~15 thousands star systems. So now imagine a civilization similar to us but slightly older, not only would this civilization's signals have reached all parts of our galaxy, but those signals would likely be much stronger than we have produced in the last 100 years. It would also be possible for a civilization a few hundred millions years older than us to send probes to every star of the galaxy by now.