We are the laws of chemistry and physics as they have played out here on Earth, and we are now learning that planets are as common as stars. Most stars, as it turns out now, will have planets.
The existence of life beyond Earth is an ancient human concern. Over the years, however, attempts to understand humanity's place in the cosmos through science often got hijacked by wishful thinking or fabricated tales.
We don't know how to identify intelligence over interstellar distances, so what we do instead is use technology for a proxy.
Earlier generations of stars in the galaxy could well have had planets. But really, there was only hydrogen and helium to work with, so they'd all be gas giants and not small, rocky planets.