We breathe oxygen because that’s what our planet gave us to survive on. It’s not the other way around – we weren’t given oxygen because we needed it. We evolved to breathe oxygen because that’s what was available.
So life on other planets might not breathe oxygen at all. They would have evolved to breathe whatever was available on their planet.
We don’t search for what we need, we learn to use what we have. That’s how we survive. That’s how a species lives.