It's not going to happen. We're early on the history of the Milky Way, but not so early that it's likely we're the first technological civilization in the galaxy. Fermi's Paradox tells us that spreading out to colonise the stars isn't happening.
Sorry guys. We live in a hard Sci-Fi setting.
Just how early or late we are to the party remains an issue of some contention - obviously we're into the 3rd generation of star formation, with a good few more to come, however studies in recent years have suggested that the universal rate of new star formation is currently at
a mere 3% of its historical peak, and will only continue declining towards the eventual heat death.
More recent studies still have nonetheless offered much more optimistic revisions to that estimate, however with regards to Fermi's paradox (and similarly, the Drake equation), perhaps the more pressing variable is the 3 billion years or so that it took for multicellular life to get a leg up.
There's been very tentative findings (just over the last few months in fact) that suggest tenuous fungal-like filaments of very basic multicellular (or just cooperative unicellular) fossil structures from very deep-earth samples may have been around
billions of years earlier than previously thought, however there's no question that for 3 billion years prior to the Cambrian explosion, there were insurmountable constraints upon diversification and proliferation of life as we know it.
Until we can eliminate the possibility of a second genesis within our own system (such as at hydrothermal vents within Enceladus's or Ganymede's cores, or likewise in the rich hydrocarbon environs of Titan etc.), it's largely guesswork as to the probabilities of even the most basic forms of life developing... but even at the most optimistic outcomes of that search, it seems evident that multicellular life is an exceedingly rare occurrence, likely made possible in our case only through the happenstance symbiosis of the mitochondrial progenitor, which is the singular factor making multicellularity even viable in terms of its energy requirements and ability to share nutrients in a homeostatic positive-feedback. Suffice to say, parasitic colonisation is most usually detrimental to the host cell, if not outright fatal. But of course it also hinges upon the need for a high degree of diversity within the unicellular lifeforms that might constitute such a cooperative union in the first place. Maybe whatever mitochondria developed from necessarily evolved in an environment substantially different to, and thus remote from, the cells it eventually became hosted by, and thus such occurrences are further precluded by the sheer geological isolation between the component organisms.
TL;DR - the chances that
we are the first technologically advanced species in the galaxy are actually far higher than one might like to imagine - purely in terms of the energy requirement of successful, mutually-profitable multicellular cooperation. Remember, that the average active Human turns over (and constantly regenerates) around 1.5 times their own body weight in adenosine tri-phosphate every 24 hours - a rate of combustion itself dependent upon the availability of free oxygen, which in turn is dependent upon the overwhelming abundance of the unicellular lifeforms we have to thank for its release into our atmosphere in the first place.. So just in terms of the raw physics, we're in an
extremely privileged position, with a hugely complex and wholly improbable sequence of incredibly fortunate coincidences to thank for our existence..
Given these unfavourable odds, it's unsurprising that Hoyle et al's
pan spermia hypothesis is seeing something of a renaissance, after 50 years of initially promising searches for abiotic spontaneous genesis have proved fruitless. We've found amino acids just about everywhere, from comets to test tubes of basic elements zapped with electricity - and even coaxed them into spontaneously self-organising closed catalytic systems (wherein the ratio of molecular species to that of the reactions they're able to catalyse forms a stable closed system)... but for all this, anything truly resembling 'life' remains well beyond our means to replicate. Let alone complex, ie. multicellular, life.