Yes, but to labour the point, the initial questions were about other alien life forms. And in that equation we can safely say it is 0.
If we include our own, it is >0, but still an infinitesimally small number.
Nothing wrong with that, but even the staunchest of scientists would agree it's more in hope than expectation that life is out there. To be honest, my initial point was to make that distinction.
But after reading some further replies, I'd say that's it's easy to glibly say that life must be out there because it occurs here. However, it underestimates some of the work done by some of the brightest minds who have done extensive and substantial work in this arena. For example, attempting to find trace molecules of elements needed for life to even begin to exist, the identification of solar systems similar to ours, the identification of Earth-like exoplanets that exist in what scientists call 'the Goldilocks zone' that can perhaps provide conditions for life to exist (i.e. neither too hot nor too cold), the number of Sun-like stars; the list goes on.
We're still at stage 1 of this exercise, and it's why I said in my first post, if it were to be discovered, it won't be anytime soon. One of the overriding themes of this research is that our part of the Universe is still relatively nascent, so we would expect or be able to detect 'noise' from advanced civilisations in other parts of the universe.
So, currently, as in 22 Feb 2021, the notion that life exists outside of our own planet is a belief in substance. And any probability provided is so close to 0 that it would be statistically insignificant according to any / most scientific and mathematical methods...but should we stop looking? No!
Here's a really informative article on how the research occurs if anyone is interested:
https://www.nationalgeographic.com/...e-probably-exists-how-do-we-search-for-aliens