Re: Cool..but also oddly disturbing
Why? Just because you have a feeling that's so?
Until recently most scientists thought Earth like planets in the habitable zone would be fairly rare. Now we found out there are billions in just our own galaxy. We don't know whether life arising is common or not, or how likely it is that intelligent life will eventually arise given a long enough period for evolution to take its course. The only way we'll find out the answer is to go look, so unfortunately we won't get an answer in our lifetimes unless some friendly alien comes along and tells us of the million civilizations out there or how we're the only other civilization he's seen in millennia of searching.
While it is possible we're "living in the cosmic era where the first civilizations start appearing", that's exceedingly unlikely given the number of planets out that capable of potentially supporting life as we know it.
The "if we're not alone why haven't we heard from anyone" could simply be that we haven't discovered the technology that civilizations typically use to communicate just yet. If we wanted to communicate off planet 120 years ago, our best bet would have been to use a lighthouse, because we didn't have radio. 50 years ago we'd have used AM or FM analog radio. Now we'd use some sort of digital transmission, which would sound like mere noise to someone who heard it a century ago.
Life has existed on this planet for 3.5 billion years, humans for several hundred thousand, and we've had the means to send radio signals strong enough to leave the solar system for barely one hundred. If we discover something new that obsoletes radio, why would we bother to continue to broadcast and listen for radio signals "out there"? We'd assume they'd use the technology that replaced it, because it is better. If the average civilization replaces radio after a couple centuries, then never listens to it again, the odds of us hearing back from anyone via SETI even if there are millions of civilizations out there is very nearly zero.