If the first man, Adam, ever changed the tracjectory of mankind right after its creation that stains the spiritual realm or failure to become perfect, we never not know. But for now, we believe the original sin exists, which is our current imperfect homosapient tendency, not as a passed-down invisible curses from our parents. Let St. Augustine call this defect, but we disagree how he further call it a 'sin'. The orthodox church happens stay inline in this consistency though they do not oppose calling the fallen 'consequence' as original 'sin'.
This view therefore denies Pelagianism. Divine Grace is the fabric of free will, without it, free will will not reach God. Righteousness isn't the goal of Christianity, but rather, the everlasting life with the Trinity. Therefore, baptism is required for salvation, not so much to remove sins, for absence of sins doesn't give anyone access to salvation.
* Disclaimer: we offer reflection, framework to seek and further Truth, without any intent to discrediting current dogmas of Catholic Churches, as the aspostels had been given power to bind in heaven, we should follow what the Church binds. Please work with your bishops and avoid this framework if it may cause confusion that lead some to leave the Holy Mother Church.