Space is big, light is slow, and the inverse square law is a thing. You think we’ve been pumping out radio broadcasts for hundreds of years and nobody has contacted us yet, but we’re only detectable to life within 200 lightyears if they’re specifically looking for the signals we pump out, and they’re looking exactly at us. We’ll only see a response if they decide to, and we can detect it, and we’re looking at them when their response reaches us, and we recognize that it’s a response and not a peryton.

It’s not a paradox, you just have to look at this Wikipedia page.