In the Bible, Adam is referred to as the first human, created by God, on the sixth day.
In humanoid galactic history, ADAM is the codename for the first earth human, created by aliens, through genetic manipulation, Adam was a cross breed of genes of earth primates and galactic -mainly Pleiadian - humanoid species.
Lyrans, Vegans, Sirians, Pleiadians, Orions and Reptilians all had their experiments. Some did not even restrict themselves to experiments with earth primates, but also used genes of other terran animals, hence the stories of centaurs, bird-men, etc.
(Though some stories about cat-people and bird-men refer to actual alien inhabitants of the Lyran system, and not to these terran cross-breed experiments).
In this context, Lyssa Royal and Keith Priest refer to Adam as "the label of the first stable prototype model of Homo Sapiens. 'Adam' comes from the Hebrew 'Adama,' meaning 'created of the Earth's Soil,' thus 'earthling.' In Sumerian, the word is 'Adapa,' meaning 'model man.' " (PoL)
Sometimes the term "Adam Kadmon" is used to refer to the Terran type of humanoid.