We are the only life form of the univers. Not even the only intelligent, but the only one. My arguments are:
Life is absolutely everywhere on earth. There is not a single isolated island or deep trench in the ocean that is not covered by life. If life can live elsewhere, univers would be covered by life. Some bacteria would have been ejected into space by some cataclysme and had colinized nearby planets. Kind of Fermi’s paradoxes.
Antropic argument. Our universe is suitable for life because if it weren’t, we simply wouldn’t be there. Add it to Okam razor. If a smaller, simpler, universe could handle life, we would be in that one. Not our current one.
“Our universe is so huge, so there must be other life form” is not the right statement. Our universe is so huge because it is the smallest universe where life could potentially appear.
Only my opinion, not a scientific demonstration.
I put it to you that we just haven’t discovered life elsewhere. FWIW, this picture says why we likely haven’t heard from life outside of our planet/solar system. Our radio signals have been travelling for nearly a century at this point, and this is as far as they’ve travelled.
I thinks there are 3 level of life discovery:
Unfortunately, I’m now convinced universe is too huge and speed of light too slow to reach step 3. A best, we would have step 2. For step 1, if life exist outside of observable universe, it’s like it doesn’t exist at all as it’s just physically impossible to detect it.
My current belief is life is so rare we are the only one in observable universe. Maybe there are few other outside of observable universe, which is much bigger, but as I said, it’s like they don’t exist at all.