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.
Just in the observable universe there are around 2 trillion galaxies. Our galaxy (pretty average as galaxies go) has more than 100 billion star systems, each of them with their corresponding planets.
Even if the average density of life is just 1 planet per galaxy (which frankly speaking, would be ridiculously low), you’d have a couple of trillion of planets with life. Intelligence of course would be scarcer, but I don’t think it’s that anomalous in the large scheme of things.