there is probably intelligent life that would be suitably capable of interstellar travel. It would seem statistically unlikely that humans are the "only" or even "the first"

We're neither, not by a very long shot, and the fact that you can even say this implies that you have not grasped the scale or scope that would be involved. We are, in fact, not significantly closer to being capable of interstellar travel now than we were three millennia ago.

Yes, we can now, in theory, build devices capable of unmanned interstellar travel; but they're preposterously expensive, wouldn't accomplish much, and would take dozens of human lifespans to reach even the nearest alien star systems and would not be able to stop when they do get there, other than by crashing into something. They might be able to radio back a little information, but the distance makes both lag and bandwidth a real problem, and absolutely positively everything would have to be entirely pre-programmed and so would be very, very primitive in terms of its capabilities compared to what NASA and similar agencies do with in-system probes, all of which receive and carry out instructions interactively as they go, generated by earth-based scientists who are looking at the data the probe just sent and deciding what to do based on it, something that would be fundamentally impossible with a multi-year communications lag (particularly given that the device would, by virtue of the nature of the mission, be moving at rather high speed, by human standards).

In fact, it is not at all clear that we will ever achieve (manned or practical) interstellar travel. We're real proud of the fact that we've achieved "space flight", by which we mean landing on the moon a couple of times and sending unmanned probes around our solar system, but interstellar flight is an entirely different matter altogether. It's like the difference between school boys putting a six-foot-long plank across a creek to get across without needing to take their socks and shoes off (or get them wet), versus building a nuclear submarine to explore the ocean under the north pole. Actually, I think it's quite a bit more of a difference than that. Even sending a data-collection probe to one very (by interstellar standards) near star system would be a logistical feat that would make all the in-system stuff we've done to-date seem like nothing. And, in turn, sending a single data-collection probe to one very nearby star system would be nothing at all compared to actually exploring the galaxy, much less the universe.

Personally, I am convinced that A) there almost certainly is not alien extra-terrestrial life in other star systems, but B) even if there were, the odd are very very low that any of it would develop practical interstellar travel and furthermore C) even if they did, we would almost certainly never find out about it, because the odds they would travel here, specifically, out of all the places they could go, are much, much lower than the odds that a multi-billionaire I've never heard of has named me in his will and will die tomorrow.