What is death according to Catholicism?
Death consists in the separation of soul and body. - Cf. Individual
eschatology, Eschatology | New Advent.
Can the body live after it is separated from the soul?
The LORD teaches that it is the spirit that gives life, the flesh is of no avail. Therefore with death, while the soul goes on, the body returns to dust from which it was taken because of itself it contributes nothing to the living person.
Cf. Also Eccl 12:7 (RSVCE): and the dust returns to the earth as it was, and the spirit returns to God who gave it.
What other scriptural passages may assist the OP in the proper understanding of Catholic teaching regarding death?
Therefore they are dead those who are taken out of the land of the living to go down to sheol, the abode of the dead.
Another expression is "putting off one's tent" as in 2 Pt 1:14 (RSVCE).
Cf. Also Phil 1:21-23 (RSVCE), where St. Paul speaks of what he gains via death, i.e., going to be with Christ.
Therefore the OP's question:
According to Catholic doctrine, why does the whole plan of redemption
depend on the physical death of Jesus Christs (sic) human body? How
are we saved from Adamic death which according to doctrine was death
of physical body only?
cannot be answered from a Catholic perspective because it seems death is understood as the "death of [the] physical body only", while the Catholic definition and understanding of death in line with scripture is that death consists in the separation of soul and body.
Cf. This answer of mine to: How is the matter of why the Son of God needed to be sacrificed explained in the Roman Catholic Church? | C.SE.