"Adam was a mythical figure who
never really lived."
Adam is a key figure in
Scripture. He is described as the "first Adam,"
the one who brought sin into the world. He made it necessary
for Jesus, the "last Adam," to atone for all
humans, and then rise from the grave with the promise
of complete redemption for fallen man and fallen creation.
If Adam was just a myth, we would not be able to fully
understand the work of Jesus. If Adam and Eve were not
real, then we ought to doubt whether their children
were real too, and their children...and then we ought
to doubt the first 11 chapters of Genesis, and so on.
All the genealogies accept Adam as being a literal person,
so their children Cain and Abel (Genesis 4:9,10; Luke
11:50,51) must be real too. Jesus was descended from
Adam, and it is impossible to be descended from a myth.