There are only two ways to get to stream-entry:
1 - being a samaṇa on alms & rags, with faith in the Buddha, Dhamma, etc. (SN 55.1)
2 - destruction of the three fetters. Of wich “sakkāya-diṭṭhi” is concerned with getting rid of the “mine” part.
If one understands what “I” and “Mine” means in Buddhism; then one has done 90% of the understanding on how to leave the kama loka.
For, to get to nibbāna, you have first to leave the kama loka; then the rupa loka loka; then the arupa loka.
Nibbāna is beyond “neither-inquiries-nor-non-inquiries” ( aka “neither-perception-nor-non-perception” ) about this paṭiccasamuppāda (Dhamma).
Or should I say more properly, that nibbāna is beyond "neither inquiries" about paṭiccasamuppāda, nor "non-inquiries" about something else.
For the transcendence of the spheres of experience (āyatanāni), are usually done (in Buddhism,) by getting rid of something - in this case non-inquiries about paṭiccasamuppāda - and looking for something else - in this case the avyakata (the unsaid - which is out of paṭiccasamuppāda).
Dhamma, or ध dha (or √ dhā) - √ मन् man - being a somewhat "performed & established “thinking” , in Indian philosophy at large.
Paṭiccasamuppāda being one of these धर्मन् dharmán (dharma).
“Neither-inquiries” about paṭiccasamupāda - (and the assumptions attached to them); as well as an inquiry beyond paṭiccasamupāda - is the last and highest of the higher jhānas.
So one has to get there, to get to nibbāna.
The first big step is to get out of the kama loka.
And that is done by getting rid of the “mine” and the “I”. See SN 22.89 (and SN 22.47), and get a good grasp of what “I” and “Mine” mean.
Realising the “Mine” part has nothing to do with concentration. It has to do with understanding that khandhas & ayatanas are not “ours” (SN 22.59, SN 22.3, SN 35.138). That we are just made to be felt (SN 12.37). It is about paññā - It is about discernment.
There is no continuity of “self” between nāmarūpa and saḷāyatana. So it is ridiculous to want to appropriate the khandhas of nāmarūpa (as “mine”) - as much as it is ridiculous to want to appropriate the ayatanas of saḷāyatana (as “mine”).
Buddhism is not like late Vedism, where Ka/Prajapati is the continuous Self/self all along. Where the Self, khandhas and ayatanas are “I” and “mine”.
There is nothing in Buddhism that belong to Ka (Kāya) - Neither continuity of Self/self; nor bliss.
What we experience sensorially is not “ours”, says Buddha.
The second part, as seen in SN 22.89, is to get rid of the “I”. And this time, it involves being aware that the dhammas, made out of the khandhas (that are not ours), are impermanent.
To get to that, one must gain concentration and gain a citta, caused to become one.
Here, bhikkhus, the noble disciple, having undertaken the relinquishing of the support, gains concentration and gains a citta, caused to become one. This is called the faculty of concentration (SN 48.9).
Idha, bhikkhave, ariyasāvako vossaggārammaṇaṃ karitvā labhati samādhiṃ, labhati cittassa ekaggataṃ—idaṃ vuccati, bhikkhave, samādhindriyaṃ.
Here, we have the particular case of a genitive absolute; with nouns (samādhiṃ & citassa,) and a participle (ekaggataṃ), both inflected in the genitive.
Samādhi is that pro-active meditative oneness of concentration that helps get to the oneness of the citta.
Getting rid of the “I” is the passage from samadhi to vipassana. From the pro-active" meditation to the “contemplative” meditation.
This is the moment when the citta gets transcended (liberated from mano), in the second jhāna (cetaso ekodibhāva).
Then vipassana can settle in.
Vipassana, that is to say the meditative concentration free of the dross of the sensory “world” (SN 35.107 & SN 12.44). https://justpaste.it/1cmhg
This is when the citta gets rid of its impurity (viz. get rid of the tie with the purely sensory orchestrator of khandhas and ayatanas, that is mano - https://suttacentral.net/en/mn43/21), and become one, and become “mudu”. AN 3.101
This is the end of the kama loka and the entrance in the factors of enlightenment per se; that is to say, the entrance in the rūpa loka.
And yes! Jhānas, particularly the higher ones, are necessary to reach nibbāna.
Liberation by discernment (paññavimutti), and liberation of citta (cetovimutti) are not nibbāna.
As one can see above, paññavimutti is about the “mine”; while cetovimutti is about the “I”.
When one has discerned that the khandhas and ayatanas are not “his”; and that dhammas, made of those, are impermanent; then one passes through the higher jhānas of the rupa loka (viz. somewhat third; and fourth Jhānas).
Then one has still to jhāna (“make an end of”) each sphere left, to get to the arupa-loka.
Each particular jhāna (absorption) carries its own jhāna (“making an end of” something). For jhāna has two meanings indeed.
The complete transcending of perceptions of form (matter), and the vanishing of perceptions (based) upon the organs of senses [internal āyatanāni] (viz. paṭighasaññānaṃ atthaṅgamā) - and the unstriving with the mind (manasa/mano) to perceptions of manifoldness (lit. (what is) differently than one) (nānattasaññānaṃ amanasikārā) - is the passage from the rūpa, to the arūpa loka. And that takes place in the 5th jhāna.
And lastly, one must get rid of each of the arupa loka spheres - to reach the last higher jhāna. For nibbāna is beyond the sphere of neither-inquiries-nor-non-inquiries (aka “neither-perception-nor-non-perception”) .
‘Homage to you, O thoroughbred person!
Homage to you, O supreme person!
We ourselves do not understand
What you meditate in dependence on.’