Is the dignity of man pertains to his soul only or to the wholeness of his being meaning body & soul?
Thou hast made him a little less than the angels, thou hast crowned him with glory and honour. - Psalm 8:5
The short answer is that the human person is composed of a soul and body, thus the dignity of the human person applies to both man’s soul and body.
"God did not make death, and he does not delight in the death of the living. For he has created all things that they might exist ... God created man for incorruption, and made him in the image of his own eternity, but through the devil's envy death entered the world, and those who belong to his party experience it" (Wis 1:13-14; 2:23-24).
42So also is the resurrection of the dead. It is sown in corruption, it shall rise in incorruption. 43It is sown in dishonour, it shall rise in glory. It is sown in weakness, it shall rise in power. 44It is sown a natural body, it shall rise a spiritual body. If there be a natural body, there is also a spiritual body, as it is written: 45The first man Adam was made into a living soul; the last Adam into a quickening spirit. 46Yet that was not first which is spiritual, but that which is natural; afterwards that which is spiritual. 47The first man was of the earth, earthly: the second man, from heaven, heavenly. 48Such as is the earthly, such also are the earthly: and such as is the heavenly, such also are they that are heavenly. 49Therefore as we have borne the image of the earthly, let us bear also the image of the heavenly. - 1 Corinthians 15 42-49
Separating man’s body from his soul man him a living being other than man? This is what happens to each and everyone of us at the moment of death, until our bodies are reunited with our souls at the Last Judgement.
Does the Catholic Church believe that we become just souls after we die?
This is why the Church technically refers to souls in Heaven as saints and not as persons. For the human person is technically composed as having a soul united with an earthly body! This will all change at the end of times!
Nevertheless, many refer to the saints in Heaven as saints. The souls in purgatory are interestingly enough referred to as the Souls in Purgatory!
Man is made in the image of God and God is Spirit. The second person of the Holy Trinity in the person of the Only Begotten Son, Jesus Christ is both truly man and truly God. Truly man because he is in his human nature composed of a human body and an immortal human soul.
- Every individual, precisely by reason of the mystery of the Word of God who was made flesh (cf. Jn 1:14), is entrusted to the maternal care of the Church. Therefore every threat to human dignity and life must necessarily be felt in the Church's very heart; it cannot but affect her at the core of her faith in the Redemptive Incarnation of the Son of God, and engage her in her mission of proclaiming the Gospel of life in all the world and to every creature (cf. Mk 16:15).
52 Man, as the living image of God, is willed by his Creator to be ruler and lord. Saint Gregory of Nyssa writes that "God made man capable of carrying out his role as king of the earth ... Man was created in the image of the One who governs the universe. Everything demonstrates that from the beginning man's nature was marked by royalty... Man is a king. Created to exercise dominion over the world, he was given a likeness to the king of the universe; he is the living image who participates by his dignity in the perfection of the divine archetype".38 Called to be fruitful and multiply, to subdue the earth and to exercise dominion over other lesser creatures (cf. Gen 1:28), man is ruler and lord not only over things but especially over himself, 39 and in a certain sense, over the life which he has received and which he is able to transmit through procreation, carried out with love and respect for God's plan. Man's lordship however is not absolute, but ministerial: it is a real reflection of the unique and infinite lordship of God. Hence man must exercise it with wisdom and love, sharing in the boundless wisdom and love of God. And this comes about through obedience to God's holy Law: a free and joyful obedience (cf. Ps 119), born of and fostered by an awareness that the precepts of the Lord are a gift of grace entrusted to man always and solely for his good, for the preservation of his personal dignity and the pursuit of his happiness. - Evangelium Vitae
John J. Coughlin Goes on to give us many insights in the following:
The mystery of the human being's creation in the image of God means that the human person has been endowed with creativity. The definitive creation of the human being is incomplete until the creation of Eve. When Adam recognizes Eve•as. a32 human being like himself, "flesh of my flesh," he is filled with joy. They are embodied spirits for whom thinking, acting, and expressing depends on the body, which is not accidental but integral to human nature.33 The divine command to the first parents-to "[b]e fruitful and multiply" - Pope John Paul II and the Dignity of the Human Being