And, if you follow this logic, it would be necessary for Mary’s mother (and father, for that matter) to also be “free from all sin” in order to avoid contaminating Mary. In other words, where was the immaculate womb for Mary? Wouldn’t this be at least as necessary as a “sinless womb” for the Sinless One if you are to be consistent?
Thus, you set up a perpetual problem, for Mary’s parents’ progenitors would have had to be sinless as well, in order not to carry forward the stain.
Correction: it would be necessary for the obtuse to conclude.
You apparently accept that, just as Scripture teaches, the Blessed Virgin Mary conceived a child in her womb without knowing man by the power of the Holy Spirit. Yet you can't accept that the same Holy Spirit could also immaculately conceive the same Blessed Virgin Mary.