Q: Why haven’t the aliens contacted us yet?
A: The short answer is, because we haven’t invented warp drive yet. (Thank you, Gene Roddenberry.)
The long answer is, because we’re a self-destructive species. We act as though we believe that skin pigmentation ought to determine one’s success in life. We exploit our natural resources to the point of poisoning ourselves and every living creature on Earth. We act shitty towards each other.
No intelligent life form can trust us to act responsibly this early in our development. We’re in no way ready to be global citizens, let alone intergalactic citizens.
Can we get ready? In my lifetime? In yours? Maybe. But not without trying.