I know you didn't ask me, but since I too am a science guy, I think I'll butt in.
Why would it be a guarantee? We don't have enough information to make that assessment. We only have evidence of life on Earth. The other planets in the solar system seem barren, but one can hope we'll find evidence of microbial life at one point. But so far, we only have Earth. Now on Earth, life seems to have only happened once. All of life on Earth descends from the same common ancestor. Why did life only evolve once? Either because those are the only viable self-replicating molecules able to sustain the level of complexity required for life, or that life evolved more than once but only a single branch won out.
In the case of the former, life would need very specific conditions to come into being and survive long enough for natural selection to take hold. If the latter is true, we would simply have no idea how common life is. We wouldn't have the data on the other possibilities. I personally think the first scenario is more likely. Assuming that it is, then life, at the bacterial level should exist elsewhere. We know that some aminoacids exist in nature. We found them on comets and in the dust of faraway nebulae. We also know that there are literally billions of Earth like planets in the galaxy, and that a portion of them is in the so-called Goldilocks Zone, with temperatures that allow for liquid water and complex chemistry to exist.
If I was a betting man, I would bet simple life exists in the galaxy. But it brings us to the next level; multicellular life. How easy is that? Single cell life existed on Earth for 2.5 BILLION years, before multicellular life decided to make an appearance, less than a billion years ago. Why did it so long? Would the process take less or more time elsewhere? If it's more, then we run the risk of expanding sun making temperature too hot for complexity (as will happen to our own solar system). Even if bacteria exists in the galaxy, who is to say bacterial planets survived in the right conditions long enough for more complex forms to emerge?
And it brings us to the last level; human intelligence. This also happened only once on Earth. In a billion years of animal life, a technological species evolved once. All of those extinction events and iteration produced a single human-level species. What are the chances of that happening? That's unknown.
It is important to keep in mind that only the galaxy is relevant, not the universe at large. Anything beyond the galaxy is too far for communication, or even detection. What are the chances another human-like creature evolved in the 200 billion or so stars in the galaxy? It is far from guaranteed.
