Absent Aliens: With one exception, the Kershkans, Parahumanity has not encountered a single extant species of sapient alien.
However, there is evidence a plenty of their existence, at some point in history, from the presence of the Destroyers and the graves of their victims. Somebody had to create the Destroyers after all. In addition, the Federation has found the remains of ten bombed out systems, Earth-sized planets cracked open by relativistic projectiles, sometimes other celestial bodies bearing craters that seem unnatural. It seems disheartening at first, but the distance between those systems suggest independent evolution, with no exostellar colonization efforts. By that standard Parahumanity is far ahead of the game.
A number of planets, such as Tau Ceti, have complex ecosystems with plant and animal analogues, but little potential for sapience, even with uplift.