Short answer: In Digambar Jainism this is not meant as “men are superior.” It is a doctrinal point about the last steps to liberation, not about the worth of women.

Key ideas, kept simple:

• The soul (jīva) is genderless. Its pure nature is the same in all beings. Spiritual worth is identical.
• Digambar acharyas teach that, in our current era, the very last stages to liberation require a form of renunciation that includes complete non-possession and nudity. Because Digambar nuns (āryikās) wear simple cloth, they are seen as unable to fulfill that specific final vow in a female body. Therefore, they hold that a final male birth is needed to complete those last steps.
• This is presented as an issue of bodily suitability for a specific discipline, not a claim that women are spiritually lesser. Women are fully capable of right faith (samyaktva), deep austerities, profound knowledge, and very high spiritual stages; many are revered exemplars.
• Different tradition: Śvetāmbars explicitly affirm that women can attain kevalajñāna and liberation in a female body. So the two traditions differ on the final step, while both agree that the soul’s essence is equal.

So, in the Digambar view, “male birth” is treated as a practical condition for the final vow in this era, not a value judgment on women. The spiritual dignity and potential of women is fully affirmed, even though the last step to mokṣa is said to require a male rebirth in that tradition.