By far the most likely resolution to the Fermi Paradox is that there aren’t any aliens capable of interstellar travel or even interstellar communication (radio or otherwise) in our galaxy. The great filter is behind us, and it consisted of the unlikely evolution of the mostly cognitive capabilities required to build multi-generational, growing civilization. This happened on Earth only once, and only a few thousand years ago. Combine thus with the absence of any sign of intelligent aliens, even though there would be strong pressures for them to spread beyond their home star, is why I believe we’re alone.
By contrast, I believe there are many independently evolved instances of biochemical life, most of them unicellular. That’s because life on Earth evolved as soon as it possibly could.
Other possible solutions are discussed here.
Nehaveigur 