Mine is probably the most boring: There are many intelligent species in the universe. Faster-than-light travel, however, really is simply impossible, meaning that there cannot exist a truly interstellar civilization. So while some species have probably settled solar systems other than their own through generation ships, suspended animation, time dilation, or whatever, their range of expansion is limited. This means that encounters between species of different planets are rare. Humans will most likely never contact any intelligent alien species, at most one or two. We might, however, discover evidence of their existence through telescopes or something.
Depends on what version of the "paradox" we're talking about, is it signals or direct contact?
If it's lack of direct contact the answer is simple, they're not going to talk to us and for good reason, you'd have to be barking mad to want to engage directly with this planet. Who would you even introduce yourself too, there are 200 nation-states most of whom have a history of inflicting savage violence on their own populace, you think any intelligent being is going to objectively look at that and think "yeah lets kick that hornets nest", the best you can hope for it that we're at least interesting enough to be the subject of extensive remote observation and study
If we're talking about signals, then it's probably because we're either not listening properly, we're not listening for long enough, or they're not transmitting signals we can detect
The thing is, any civilization capable of coming here from another star is far enough beyond us that we pose no threat.
Sure, you could say that they have nothing to gain from introducing themselves to this mess, but there would have to be some kind of deliberate extreme quarantine if they can prevent every member of an alien civilization from making contact individually.