Re: “we don’t really know what to look for when searching for civilization more advanced that ours”

I like Babylon 5’s concept of elder races in this regard. As G’Kar explains in S1, E6 “Mind War”:

There are things in the universe billions of years older than either of our races. They’re vast, timeless, and if they’re aware of us at all, it is as little more than ants, and we have as much chance of communicating with them as an ant has with us. We know, we’ve tried, and we’ve learned that we can either stay out from underfoot or be stepped on.

I feel like this is what NHI would look like to us. It would probably look like gods. I am also with Hawking: We probably don’t want to come across alien life. The best case scenario is that it doesn’t care about us. Or we might get stepped on, like G’Kar suggests. Worse case, they just come and eat us. Or strip mine our solar system.