Who is Adam?

1 Corinthians 15:45-50 KJV 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.