What is the common understanding of all enlightened people? There are many sutras and they are on different topics. Many people got enlightened by asking different sutras. Ven. Saripuththa thero got sothapanna by asking to cause and effect. Ven. Kondanna thero got sothapanna by asking to middle path and kamma. So, What is the core teaching of all the suttas ? What wisdom all they have in common ?

Edit: I think all people have some understanding of the world. Lord Buddha recognized those and help them to complete their understandigs. Ex: When Ven. Sariputhta thero hearing to the Cause and effect, He already have the understanding of Impermanance. (Because of that, He started to find the truth).
As others have already answered, the four noble truths are the wisdom held in common by the teachings of the Buddha that lead to enlightenment. As the Buddha said in his first discourse,

&quot;As long as my knowing and seeing how things are, was not quite purified in these twelve aspects, in these three phases of each of the four noble truths, I did not claim in the world with its gods, its Maras and high divinities, in this generation with its monks and brahmans, with its princes and men to have discovered the full awakening that is supreme.
(Nyanamoli, trans.)

Sariputta's attainment of sotapanna is a good example of how the four noble truths are both necessary and sufficient for enlightenment, as what you call cause and effect is actually a concise teaching on the truths, as the commentary relates:

ye dhammā hetuppabhavāti hetuppabhavā nāma pañcakkhandhā; tenassa dukkhasaccaṃ dasseti.
&quot;Those dhammas that arise based on a cause&quot;: Those things that arise based on a cause are the five aggregates. By that he showed the truth of suffering to him.
tesaṃ hetuṃ tathāgato āhāti tesaṃ hetu nāma samudayasaccaṃ; tañca tathāgato āhāti dasseti.
&quot;The cause of them was told by the Tathagata&quot;: the cause of them is the truth of the origin of suffering. &quot;And the Tathagata spoke that,&quot; he caused him to see.
tesañca yo nirodhoti tesaṃ ubhinnampi saccānaṃ yo appavattinirodho; tañca tathāgato āhāti attho. tenassa nirodhasaccaṃ dasseti.
&quot;And the cessation of them&quot;: the cessation by non-manifestation of both those two truths - &quot;And the Tathagata spoke that,&quot; is the meaning. By that he showed him the truth of cessation.
maggasaccaṃ panettha sarūpato adassitampi nayato dassitaṃ hoti, nirodhe hi vutte tassa sampāpako maggo vuttova hoti. atha vā tesañca yo nirodhoti ettha tesaṃ yo nirodho ca nirodhupāyo cāti evaṃ dvepi saccāni dassitāni hontīti.
But here the truth of the path is not explicitly shown; it is however shown implicitly. For when cessation was said, the path leading to it was also said. Either that or: &quot;And the cessation of those&quot; here means &quot;the cessation of those and the means to cessation,&quot; thus the two truths are both shown.

Good evidence of the need to teach the four noble truths to attain enlightenment exists in the Dhānañjāni Sutta (MN 97), where Sariputta fails to teach the four noble truths and the listener goes to be reborn in the Brahma world. As the commentary says:

kālaṅkato ca sāriputtāti idaṃ bhagavā “tatrassa gantvā desehī”ti adhippāyena theramāha. theropi taṃkhaṇaṃyeva gantvā mahābrahmuno dhammaṃ desesi, tato paṭṭhāya cātuppadikaṃ gāthaṃ kathentopi catusaccavimuttaṃ nāma na kathesīti.
&quot;And he has made an end to time [i.e. died], Sariputta&quot;: this the Blessed One said to the elder with the intention, &quot;having gone there, teach him.&quot; And the elder, at that very moment having gone, taught the dhamma to the great brahma. From that moment on, even when teaching a four line verse, he never again taught anything devoid of the four truths.