

Water is extreemly common in the universe. It also enables a lot of useful chemistry that complex molecules need. In turn it is reasonable to expect water is part of all life - not a given but most of the other options rely on something far less likely to occure.
This assumes there is life. Not a debate I’m touching. Although if there is physics is against us ever discovering it. Even if earth is an extreem outlier in taking so long to develop intelligent life and every other star has it in a few hundred years few will ever detect another lifeform



Water is very common. Others might or might not work. Most ofthe others are rare. (Amonia is not rare, I have no idea how useful it might be)