So, it is clear that Nibbana can be attained via different ways by people with different “gathi” (types of individuals).
It seems to me that there are three key elements involved regardless:
1. One must get rid of the ten types of mica ditthi, and get to the mundane eightfold path.
2. One must hear/read about the correct version of Tilakkhana (anicca,dukkha,anatta), i.e., the real nature of this world as revealed only by a Buddha.
3. Then one becomes a Sotapanna Anugami and contemplates on the Tilakkhana. At some point, the essence of Tilakkhana “sink in” to the mind, and one becomes a Sotapanna.
At that point, one gets on the lokottara (Noble) Eightfold Path to the higher stages of Nibbana.
By the way, one does not need to know which type of individual one is, even though one may have an idea. As one follows the Path, one will be directed automatically by Dhamma itself: “dhamme ha ve rakkati dhammacari”.