What's out there?
Based on the number of stars, potential planets around each star, planets at a sufficient distance away from said star, or binary star systems, etc... capable to support life as we know it within the confines of physics... even silicon-based life being a theoretical possibility...
Probably lots.
If time travel were possible, somebody would have changed causal history by now - at least relevant to their sphere of influence, which is very small or very big if they decided to go back to when the universe begin and whip out a fire extinguisher to put out the alleged fire.
The laws of physics making space travel possible - this fits into Darwin's law. Not because of species adapting to climates to prosper but because a fence isn't always a bunch of sticks half-buried into the ground that people can tunnel under or pole vault over. The distances involved make it difficult for any species to waddle on over to say "Hi, may I eat you for breakfast?" like what they did in that 1983 "V" miniseries.
Which reminds of another reality, not all species get developed or develop at the same rate of time or during the same time. Chances are, if we ever figure out how to travel FTL and end up in Andromeda in x number of months (LOL. good luck to that) so forget that and let's all hang out at Proxima Centauri, assuming we don't need to terraform it due to temperatures (like how we all bought such DIY kits during Black Friday deals 2017), or too elliptical or other nonstandard orbit causing problems with the atmosphere, or other irregularities. Number of moons, rotational spin... equatorial region in relation to the sun... magnetic fields, solar flares...
'Dang law of probability...
Religions just teach people how to be nice to one another via metaphor and parable. Even the non-religious want people to be nice to one another. Yup, that's just a tad oversimplified but that's okay for now... But "Adam and Eve", if taken literally, is arguably more disgusting than taking it as a parable or metaphor. But a parable or metaphor for what? That one's easy, but compared to actual incest what isn't nasty? And how come nobody with STEM science could figure out dozens of centuries ago that inbreeding, promiscuity, etc, were bad juju long before Darwin said it was a no-no, never mind medications that have only delayed the problem and also created "superbugs" in some cases but most of that is due to people not washing their hands at work because the sign said "Employees must wash their hands (thus customers don't need to)"? Or was that Mendel, it's so terribly easy to mix those two up and inheritance isn't just nomenclature for augmenting computer programming functions... Indeed, wasn't Darwin also an ironic example of inbreeding as was recently discovered?
In other words, I think we're all what we got on this sad blue/green/beige/brown/puke planet. That we'll ever get to tangibly know about. Nature has a habit of repeating, recursive themes, so I have zero surprise of alien species on other planets existed. The fact any of them would make it here would be as intriguing as it would be very rare. Even more rare if any of them wanted to date me...