Who Sinned First: Satan Or Adam?

Someone asked this question, guys, so I
thought I share it here, let's hear what
you think. I'm sure we have well
grounded, sound bible students here.
Plaetton asked:
Who committed the first act of
disobedience and usurped the blissful
paradise of peace of both heaven and
earth? Was it Satan or Adam?
If it was Satan, common sense would
have required God to shield the newly
created earth, especially impressionable
newborns like Adam and Eve, from the
influences of Satan .
To have allowed that to happen would
have been gross negligence of the
highest form. Even more absurd is the
fact that the impressionable newborns
are thereafter punished for an event
that should not have happened if the
right measures had been taken.
Even more absurd is that the innocent
offsprings of Adam and Eve are
condemned for eternity for no sins of
their own , but for the lapse in
judgement of the first Babysitter.
God allowed Satan to roam free
knowing fully well that naive couple like
Adam and Eve would be susceptible to
his charms, which begs the question:
What was God's game plan? What's the
point of telling Adam not to eat the
forbidden fruit and yet allow the serpent
to slunk about, unchecked?