That sounds like a catch-22. Adam did not sin until he ate of the fruit, but he also was not corrupted until he ate of the fruit. How could he sin before he sinned, or be corrupted before he was corrupted?
He sinned by eating the fruit and by eating the fruit, it corrupted his body and he would die. He passed down that corruptness to everyone. At the resurrection of the body of Christ, we will put off this corruptible body and put on an incorruptible, immortal body.
1 Corinthians 15
42 So also is
the resurrection of the dead. It is sown in corruption; it is raised in incorruption:
43 It is sown in dishonour; it is raised in glory: it is sown in weakness; it is raised in power:
44 It is sown a natural body; it is raised a spiritual body. There is a natural body, and there is a spiritual body.
45 And so it is written, The first man Adam was made a living soul; the last Adam was made a quickening spirit.
46 Howbeit that was not first which is spiritual, but that which is natural; and afterward that which is spiritual.
47 The first man is of the earth, earthy; the second man is the Lord from heaven.
48 As is the earthy, such are they also that are earthy: and as is the heavenly, such are they also that are heavenly.
49
And as we have borne the image of the earthy, we shall also bear the image of the heavenly.
50 Now this I say, brethren, that
flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption.
51 Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed,
52 In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound,
and the dead shall be raised incorruptible, and we shall be changed.
53 For this corruptible must put on incorruption, and this mortal must put on immortality.