I remember that, not sure in what story it happened though. Not sure it's canon anymore. Mostly due to the roles of Galactus, Death and Eternity seems to have been redefined as new enteties have been introduced.
Not sure how the Phoenix works in that context. For me the important part of the cosmic enteties is who introduced them. Gruenwald handled Infinity and Oblivion. He tied Infinity to the quantum bands and gave her dimension as the source of their power. Making the claim that kree invented them a bit odd. Mostly becasue it further complicates the massivly powerful items the kree has invented yet they still get their asses handed to them from everyone they meet.Eternity and it's other side Infinity represents life and immortalness , death death, oblivion the lack of exsistence, and equity the balance between the these within life's struggle to survive, life is linked to the Phoenix force, which is a force of death and rebirth for universes, it's power combined with the universe/multiverse it's comes from creates the next ( and also galactus in the universe prior to the one before the current one)- see the xmen Jean Grey and mkraan crystal for more on that
Starlin I believe introduced master hate and mistress love in Silver Surfer. Death, eternity, order, chaos, inbetweener are Kirby/Lee creations I believe. The importance of who created them is relfected in who decides to use them. Some enterily skip Gruenwalds creations. Others even skip what Starlin created.
The abstract bodies where introduced by Gruenwald i believe. A clever concept that explains why they can appear and talk to ordinary people.There's also order and chaos and their balance represented by the being the in-betweener
death, eternity, Infinity, order, chaos, oblivion, pheonix are not literal life forms but more forces of nature called abstracts, galactus and the inbetweener are alive ish, but represent abstract concepts too
As with Galactus the Celestials power levels fluctate immensly between stories.The celestials are galactus level beings who judge and stimulate life's evolution, a bit like life's gardeners, they have hosts, the first came from the first version of the multiverse which at the tine was only a singularly vast universe sort of
There are also a sort of ranking where lesser enteties like anomoly exist in the same category as eternity yet the span between their importance and power is massive.there's other abstract concepts too, love, hate, and other cosmic powers like eon and epoch, the promeal gods and the infinites, there either less important or less commonly used
I wish Hickman wouldn't have gone down that route.There's also the beyonders who sit outside of reality and likely outclass all of these except the one above all, see secret wars for these