This is an interesting idea, but the answer is far from obvious. Assume
that there are 100 universes where intelligent life is so unlikely to occur
that it only happens on one place and 1 universe where it is a bit more
likely so it exist on 900 planets. Then there is 90% probability that we
live in the last one, even if most of the universes where life can occur
are more hostile.

I cannot assume this. I can assume that there is 1 universe where it
is a bit more likely so intelligent life exists on 2 planets.

By observing how common life is we may then draw some conclusion about
exactly how sensitive the parameters are that control the likelyhood of
life in the universe, although obviously statistics based on a single
sample is chancy.

Life is common on the Earth only

Radi Khrapko