A star formed as a first generation after condensing from gravitational differences in the primordial soup of plasma in the early universe. That star burned, formed a gravitational well around it and finally exploded. While it was burning it was fusing nuclei to mostly produce the first eight or so elements of the Mendeleev table. When it exploded it produced heavier elements, i.e., with larger nuclei, and it also left ready material for another star after that to be formed. Even if the star became a black hole, a black hole can help the birth of newer stars by spinning that material around itself and ejecting it out through it's poles - the event is easily ''observable'' in a Quasar, for example. After the first generation star has ejected all of it's fused and un-fused material, a second generation star may be born. Our sun - Sol, is just such a star. That star forms a gravitational well of it's own, and in that well - smaller ones yet. Those become planets and planetoids, and all the rest of their smaller cousins that ''use'' the heavier elements to form a body. On these bodies the elements produced by the first generation star and the energy from the second generation star form chemistry to produce life. Life at it's most basic core is about transfer of information. Water is the ultimate, and also most common solvent in the Universe. Carbon and Oxygen are number 6 and 8 in the Mendeleev able. Oxygen reacts violently with almost any other element out there - and certainly with all those bellow 10, except Carbon. Carbon is the only element that appears in such an abundance that can also form relatively consistent chemical bonds with a number of other elements, Oxygen included. In other words Carbon is the ultimate base because it can more easily decouple itself from Oxygen. Water is the ultimate carrier of raw bits of information, and Carbon is the ultimate base to use those bits. Having said all that - there is a very real and high statistical chance that other life in the Universe may not be so different from our own, i.e., based on Carbon and Water. Just think about it. A second generation star providing the most suitable conditions for a plethora of chemical reactions to form is made most easy in the presence of liquid water. Other sentient life in the Universe may not be so different from us... Having said that I am really not sure I'd want to establish contact - we, humans, are difficult to describe. For every positive there's an equal, sizable and considerable negative. If one is driven by intellect, discipline and integrity, I guess all is well, but those cases are so few and far in between that you can say they are vanishingly small.