Of course even the Jivanmukta is not God or Isvara himself. If every Jivanmukta becomes Ishvara then there will be many Ishvaras with powers to create, preserve and destroy the universe. Then when one Ishvara wants to preserve the universe another Ishvara may want to destroy it. This is a formula for chaos. This is why scripture makes it clear that no Jiva can become God or Ishvara Himself.
Fate of the Liberated soul
Except overlordship (on the world), they become equal to Brahma in
affluence, glory, form (appearance) and objects.
Vayu Purana I.7.29
So what is the meaning of the Advaita position that the Atman is Brahman?
Philosophical Conception of Ishvara
Who is Ishvara? Janmadyasyayatah - "From whom is the birth,
continuation, and dissolution of the universe," - He is Ishvara - "the
Eternal, the Pure, the Ever-Free, the Almighty, the All-Knowing, the
All-Merciful, the Teacher of all teachers"; and above all, Sa
Ishvarahanirvachaniya-premasvarupah - "He the Lord is, of His own
nature, inexpressible Love." These certainly are the definitions of a
Personal God. Are there then two Gods - the "Not this, not this," the
Sat-chit-ananda, the Existence-knowledge-Bliss of the philosopher, and
this God of love of the Bhakta? No it is the same Sat-chit-ananda who
is also the God of Love, the impersonal and personal in one. It has
always to be understood that the Personal God worshipped by the Bhakta
is not separate or different from Brahman. All is Brahman, the One
without a second; only the Brahman, as unity or absolute, is too much
of an abstraction to be loved and worshipped; so the Bhakta chooses
the relative aspect of Brahman, that is Ishvara, the Supreme Ruler. To
use a simile: Brahman is as the clay or substance out of which an
infinite variety of articles are fashioned. As clay, they are all one;
but form or manifestation differentiates them. Before everyone of them
was made, they all existed potentially in the clay, and, of course,
they are identical substantially; but when formed, and so long as the
form remains, they are separate and different; the clay-mouse can
never become a clay-elephant, because, as manifestations, form alone
makes them what they are, though as unformed clay they are all one.
Ishvara is the highest manifestation of the Absolute Reality, or in
other words, the highest possible reading of the Absolute by the human
mind. Creation is eternal and so also is Ishvara........Those who
attain to that state where there is neither knower, nor knowable, nor
knowledge, where there is neither I, nor thou, nor he, where there is
neither subject, nor object, nor relation, "there, who is seen by
whom?" - such persons have gone beyond everything to "where words
cannot go nor mind", gone to where the Shrutis declare as "Not this,
not this"; but for those who cannot, or will not reach this state,
there will inevitably remain the triune vision of the one
undifferentiated Brahman as nature, soul and the interpenetrating
sustainer of both - Ishvara. ..... Bhakti, then, can be directed
towards Brahman, only in His personal aspect. "The way is more
difficult for those whose mind is attached to the absolute!" Bhakti
has to float on smoothly with the current of our nature. True it is
that we cannot have any idea of the Brahman which is not
anthropomorphic, but is it not equally true of everything we know? The
greatest psychologist the world has ever known, Bhagavan Kapila,
demonstrated ages ago that human consciousness is one of the elements
in the make-up of all the objects of our perception and conception,
internal as well as external. Beginning with our bodies and going up
to Ishvara, we may see that every object of our perception is this
consciousness plus something else, whatever that may be; and this
unavoidable mixture is what we ordinarily think of as reality. Indeed
it is, and ever will be, all of the reality that is possible for human
mind to know. Therefore, to say that Ishvara is unreal, because He is
anthropomorphic is sheer nonsense. It sounds very much like the
occidental squabble on idealism and realism, which fearful-looking
quarrel has for its foundation a mere play on the word "real". The
idea of Ishvara covers all the ground ever denoted and connoted by the
word real, and Ishvara is as real as anything else in the universe;
and after all, the word real means nothing more than what has now been
pointed out. Such is our philosophical conception of Ishvara.
(The Complete Works of Swami Vivekananda III.37-42)