Q: It is commonly perceived that mastering spirituality would enable one to be emancipated from the cycle of birth and death. But, don’t you think that such a perception is flawed because its selfish in nature?

A: Why would it be “selfish”?

Q: It gives more priority to the individual self (atman) as opposed to the  transcendental self (paramatman)?

A: This does not make sense to me. Susan lives in Portugal. I cannot interact directly with her if I live in Antartica. John is on Discord. I am not on Discord, so I cannot interact with him. Paramātmā is emancipated. I cannot access or interact with paramātmā if I am not emancipated. The entire purpose of emancipation is to obtain direct interaction with Paramātmā. There is no selfish intent in mokṣa. As long as there is selfish intent, there cannot be mokṣa.

When avatars keep on incarnating every once in a while and they volunteer to confine themselves within the cycle of human birth and death, why should we strive to overcome it and take recourse to spirituality for that end?

Avatars are called avatāra precisely because they do not “confine themselves within” anything. -tāra means that they affect something inside a system while being outside that system. ava- means their position outside the system is “above” it.

Krishna explicitly corrected you in Gita: avajānati maṁ mudha, manuṣya-tanum āśrita: “People who think I have confined myself to a human form are fools.”

A person within the system of avidya cannot really help anyone. Only a liberated, emancipated being can help the un-emancipated.