In the philosophical schools of Taoism, there really isn't much of a creation myth. The most detailed equivalent to the Biblical book of Genesis is only one stanza in a brief chapter from the Tao Te Ching (Dao De Jing):
"Tao gives birth to one,
One gives birth to two,
Two gives birth to three,
Three gives birth to ten thousand beings.
Ten thousand beings carry yin on their backs and embrace yang in their front,
Blending these two vital breaths to attain harmony."
The idea is that Tao is the equivalent of nothingness or void that one finds in several traditions' creation stories. From it, the One was born, some sort of undifferentiated Something that might be compared to the Hindu concept of nirvana. The One then splits into darkness and light and all the other dichotomies that are included within the concepts of yin and yang, the two. When the two unite to form the yin-yang symbol or Supreme Ultimate, that is the three. From the Supreme Ultimate (yin and yang together) were born the ten thousand things.
The number ten thousand in this context is not an exact number in Chinese. Traditionally, ten thousand was thought of as such an unimaginably big number that it became the equivalent of infinity. The concept includes everything you can point to or even name -- all of reality.
It is sometimes translated as the "myriad creatures" or the "ten thousand beings," but that makes one falsely assume that the concept includes only living creatures. The ten thousand things also includes inanimate objects (such as rocks, buildings, stars), emptiness (like outer space or vacuums), and abstractions (such as dreams, thoughts, principles, beliefs, language, the Internet).
The concept of the ten thousand things is important in Taoism for several reasons. It distinguishes the world of manifestation from the mystical conepts of Tao, yin, and yang, for example.
It helps students of Tao to recognize the underlying connection and unity between all people and all animals and all plants and all things and all ideas. By recognizing the many manifestations, it sometimes brings us back to an awareness of the unity from which they all have sprung. Hopefully, it helps us to keep from judging things outside ourselves as better or worse than we are.
Translating the concept as "every being" or "all beings," Stephen Mitchell's interpretation of chapter 51 or the Tao Te Ching talks of the ongoing relationship between Tao and the ten thousand things:
"Every being in the universe
is an expression of the Tao.
It springs into existence,
unconscious, perfect, free,
takes on a physical body,
lets circumstances complete it.
That is why every being spontaneously honors the Tao.
"The Tao gives birth to all beings,
nourishes them, maintains them,
cares for them, comforts them, protects them,
takes them back to itself,
creating without possessing, acting without expecting,
guiding without interfering.
That is why love of the Tao is in the very nature of things."