"Of course we could tell if it was life or not if we studied it. Life exhibits certain traits and we can observe those traits."

That's a pretty broad assumption, Jack? Are you sure? Are you 100% sure?

Why, your body might be literally crawling with alien life that you are blissfully unaware of and which we presently have no scientific instruments capable of detecting! Think about that when you lie down to sleep tonight. ;-D

But I agree fully with this statement: "if easy interstellar travel exists, the ones (beings) with similar requirements to ours would be the most likely to interact with us."

Exactly. That's a very relevant point. A "fire" being, for instance, would probably prefer visiting stars than visiting Earth-like planets. (just an analogy to illustrate the point)