Tzelem and Demus cannot refer to a physical description of the being known as Adam. That is since Hashem is not in any way physical, the "likeness" means that Adam was created with the possibility of free will and with a spiritual dimension. Thus, the physical appearance does not matter in that respect. The being known as Adam was created as a "unity" with both male and female aspects in order to teach "him" that it was not possible (within this world) to live "alone". That is why he was initially created alone and the "split" into Adam and Chava.
Additionally, Hashem did not create a man and a woman seperately in order to teach the lesson that "all men are created equal". One must learn this lesson that we are all (men and women) from the same unique creation.
For example:
Men & Women: Jewish View of Gender Differences
To get a clear picture of the Jewish view of womanhood, we must go
back to the beginning – the Torah.
In the first chapter of Genesis, the Torah chooses to refer to Adam in
the plural: God created the man in His image; in the image of God He
created him, male and female He created them. And God blessed them.
(Genesis 1:27-28)
Why "them"? This was before the creation of Eve!
The Jewish Oral Tradition provides us with a fascinating insight into
this grammatical oddity. The first human, it tells us, was really an
androgynous being, both male and female in one body, sophisticated and
self-sufficient.
But if God had created such a complete human being, why the later
separation into two parts, into Adam and Eve? As God is the source of
everything, self-sufficiency would be a spiritual defeat. The answer
given is that God did not want this first human creation to be alone,
for it would then possess an illusion of self-sufficiency. Note that
there is no word for "independence" in classical Hebrew. (What we use
now, atzma'ut, is of modern vintage.) The concept of independence
doesn't exist in Jewish tradition. Aside from God, nothing and no one
is really independent. Since we are supposed to ingrain into ourselves
that God is the source of everything, self-sufficiency would have been
a spiritual defeat. God wanted to fashion the human being into two
separate people in order to create a healthy situation of dependence,
yearning, and mutual giving. Human beings are not meant to be alone
because then they would have no one to give to, no one to grow with,
and nothing to strive for. To actualize oneself spiritually, a human
being cannot be alone.
Why Not Identical Twins?
But why, then, didn't God create two identical beings? The answer is
that in order to maximize giving, the recipient must be different from
the giver. If the two are identical, giving can occur, but it is
limited. One would give based on his or her own needs, since the
receiver would have the exact same needs. To truly be a giver, the
person must take into account what the receiver needs and not only
what the giver wants. By giving to someone with different needs, a
person is trained to think and give on terms other than his or her
own.
We see, then, that the separation had to be into two different beings,
in order for us to learn to appreciate, love, give, and care for those
unlike ourselves. This is fundamental to all moral and spiritual
growth. We can also understand why God didn't just create two beings
from the start: by starting as one, we can know and feel that our life
partners are our true complement, that we need them and their
differences just as they need us and ours.
Gender Differences
The Torah is a path to self-actualization, to spiritual growth. We
have seen that in order to grow, a person cannot be alone. Therefore
two beings were created. To maximize growth, the beings need to be
different, and so men and women were created as different beings.