In Romans 5:14, it reads, "...Adam...who is a type of Him who was to come.
Strange - how can Adam, with his sinful nature, be a type of Christ, the sinless One?
Well, in two ways:
First, each one identified with the transgressor(s):
Adam, with Eve
Jesus, with all mankind
Second, each one affected the entire race:
Adam - all mankind is born under sin, regardless
Jesus - all mankind is justified through Him, regardless.
:8 But God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us...
:14 Nevertheless death reigned from Adam until Moses even over those who had not sinned in the likeness of Adam's offense, who is a type of Him who was to come.
:15 But the free gift is not like the transgression. For if by the transgression of the one the many died, MUCH MORE did the grace of God and the gift by the grace of the one Man, Jesus Christ, abound to the many.
For a beautiful picture of this wonderful work of God in Christ Jesus, read the whole of Romans 5...and rejoice that "..as through the one man's disobedience the many were made sinners, even so through the obedience of the One, the many will be made righteous" (:19)