The original sin in Adam's descendants is mortality, not sin or guilt.
"Blessed be God, who alone does wonderful things! You have seen how numerous are the gifts of baptism. Although many men think that the only gift it confers is the remission of sins, we have counted its honors to the number of ten. It is on this account that we baptize even infants, although they are sinless, that they may be given the further gifts of sanctification, justice, filial adoption, and inheritance, that they may be brothers and members of Christ, and become dwelling places for the Spirit" [St. John Chrysostom, Third Baptismal Instruction, no. 6]. Sinless as in free of personal sin, but infants are not without original sin.
Baptism is not simply about the remission of sins, but about giving the person baptized a real and living participation in the divine life.
Adam's sin makes him subject to death, and it is the mortal condition that he passes on to his descendants. Now because all men are mortal - in the likeness of Adam - they fall into sins as they attempt on their own power to maintain their existence without God. Baptism - in the case of an adult - washes away a man's sins, while also imparting to him the other gifts mentioned by St. John Chrysostom in his Baptismal Instruction. While - in the case of an infant who has not sinned - the mystery of Baptism imparts the "gifts of sanctification, justice, filial adoption, and inheritance, that they may be brothers and members of Christ, and become dwelling places for the Spirit," as St. John said. In other words, the holy mystery of Baptism gives children all the other gifts that St. John Chrysostom mentioned in his homily, but it does not remit sins in the case of a child because the child has no sins to remit.
Just to be clear, do you agree with the teaching on original sin as outlined in the Catechism of the Catholic Church?The consequences of Adam's sin for humanity402
All men are implicated in Adam's sin, as St. Paul affirms: "By one man's disobedience many (that is, all men) were made sinners": "sin came into the world through one man and death through sin, and so death spread to all men because all men sinned."289 The Apostle contrasts the universality of sin and death with the universality of salvation in Christ. "Then as one man's trespass led to condemnation for all men, so one man's act of righteousness leads to acquittal and life for all men."290403
Following St. Paul, the Church has always taught that the overwhelming misery which oppresses men and their inclination towards evil and death cannot be understood apart from their connection with Adam's sin and the fact that he has transmitted to us a sin with which we are all born afflicted, a sin which is the "death of the soul".291 Because of this certainty of faith, the Church baptizes for the remission of sins even tiny infants who have not committed personal sin.292404
How did the sin of Adam become the sin of all his descendants? The whole human race is in Adam "as one body of one man".293 By this "unity of the human race" all men are implicated in Adam's sin, as all are implicated in Christ's justice. Still, the transmission of original sin is a mystery that we cannot fully understand. But we do know by Revelation that Adam had received original holiness and justice not for himself alone, but for all human nature. By yielding to the tempter, Adam and Eve committed a personal sin, but this sin affected the human nature that they would then transmit in a fallen state.294 It is a sin which will be transmitted by propagation to all mankind, that is, by the transmission of a human nature deprived of original holiness and justice. And that is why original sin is called "sin" only in an analogical sense: it is a sin "contracted" and not "committed" - a state and not an act.405
Although it is proper to each individual,295 original sin does not have the character of a personal fault in any of Adam's descendants. It is a deprivation of original holiness and justice, but human nature has not been totally corrupted: it is wounded in the natural powers proper to it, subject to ignorance, suffering and the dominion of death, and inclined to sin - an inclination to evil that is called "concupiscence". Baptism, by imparting the life of Christ's grace, erases original sin and turns a man back towards God, but the consequences for nature, weakened and inclined to evil, persist in man and summon him to spiritual battle.