Detectable by us, yes, but not by Alpha Centauri
Yes, we can detect our own transmissions. Which isn't surprising, given that they are designed to be received by us and that they occur on and just above our own planet.
But even people living on a world orbiting the closest stars to us would miss our broadcasts if they were using equipment like ours. It would need to be 5000 times more sensitive than what we're using to have a chance of picking up our transmissions.
None of this even touches on the many other problems inherent in detecting signals over interstellar distances.