Yes, Marcia, I certainly agree with your purport. Just consider that a middle-of-the-road position in the spirit of the Drake equation might lead one to suppose that, during the life of a galaxy the size of the Milky Way, perhaps several hundred supercivilizations (those that got over the hump of "sustainabaility") might arise (as you suggested, other of the 100 billion galaxies accessible to our optical instruments more than make up for a more pessimistic numerical outlook, not to mention parallel universes, etc).

These successive SCs would emerge every few million years expressed in earth time. The evolutionary time separating them from each other would be so great that no meaningful exchange of ideas would be possible. And to suppose that a culture several million years our senior would be dinking around with radiotelescopes is laughable. The limits of physical possibility now understood by our primitive science would have long before been surpassed.

However I feel it is very likely that development of life on Earth has surely been monitored by advanced SCs since long before H sapiens, and now continues to be monitored. Whether there are (undetectable) interventions now and then is anyone's guess, but why not?

If our culture is not in the category of a flash in the pan (as are probably over 90% of emergent intelligent social orders), then we might be a phenomenon of great interest to the older surviving cultures, the youngest emergence in our galaxy anyway with possible SC potential.