Evolutionary biologist here. I think it’s highly unlikely.

It has taken about 4 billion years for intelligent life to have appeared on our planet (if you include the earth forming part), or 3.5 billion years (if you include when life first formed) to get our first “intelligent life.” By intelligent life here, I’m talking about technology in tool using and civilization building, to be clear. It’s a label I’d apply to our many of our ancestral and most closely related species. I believe much of life on earth is intelligent to the point of having things like theory of mind (the knowledge that one is a thinking individual interacting with other thinking individuals), including some birds and octopuses. The birds and octopuses part is important because it means that ToM evolved multiple times independently. That means that a) it’s a “good idea” (it has potentially significant adaptive value) and b) it’s possible to discover it along multiple pathways. Take eyes for example. Last time I looked, we believe eyes have evolved independently at least 24 times. They also exist at every stage of complexity and in a very wide variety of forms, and even something as as simple as being able to tell light from darkness has value.

However, in that 3.5 billion year history, intelligent life evolved exactly once, from a single line of descent. Intelligence such as ours is obviously a good idea. We went from being relatively unremarkable hominids to being the dominant life form on the planet, for better and for worse. Evolution is not moving all species to intelligence. Humans aren’t the point of evolution, any more than sharks or jellyfish are the point of evolution.

When such a manifestly good idea only evolves once, from a single line, the conclusion is that it’s pretty difficult to evolve. It might require a chain of preliminary mutations, or a particular environment. Being hominids, for example, we can make tools and carry fire, which dolphins and octopuses cannot. Of course, there are other hominids out there who do not do those things, and they’ve been around for millions of years. Depending on where you want to start the clock, they’ve been around for about ten times longer than modern humans - about 400k years, give or take. And the technology and civilization part has only been around for the last tenth of that, and has to evolve along its own, non-biological selection - and even those things differ wildly between different places and cultures. And even will all that, it’s become increasingly obvious that this might be a terminal mutation as the very drivers of our short term success may lead to our extinction.

I believe that extra-solar life probably exists. Whether it exists as bacterial mats or multicellular life, whether it’s discovered its own form of photosynthesis or has some other way of gathering life from its environment, whether it draws a distinction between its informational (eg, dna) and physical components - I have ideas but obviously no data.

In any case, that’s why I don’t believe that anyone has ever seen an extraterrestrial-origin ufo. I don’t believe the universe ever was nor will ever be teeming with civilizations.

All of that said, though, we’re dealing with an n of 1. We can make the best inferences possible based on what we can observe, but I would be delighted to be proven wrong tomorrow. I’m a sci fi nerd - I want there to be aliens. Even the discovery of a bacterial mat would revolutionize biology.