As Crab Bucket rightly states:
The answer is not to concern yourself with such matters. The Buddha
teaches one thing and that thing is liberation.
If you were to refer to a theory of Creation in the time of the Bhudda, the closest occurence of it would be the dualist cosmology of the Samkhya. For philosophy was the leading current of thought at the time (rationalization & systematization of the metaphysical, religious and ritualistic Brahmanism;) and Samkhya was its leading philosophy, before Buddhism perfected it.
The Samkhya sees creation as follows:
The Samkhya system espouses dualism by postulating two irreducible, innate and independent realities: Purusha (the Cosmic Being(s)) or Self(ves,) and Prakriti (the phenomenal realm of Nature).
Purusha: the “controller” is intelligent, indifferent and inactive, yet pervasive.
Prakriti: has all the powers (latent, potential and actual) and is active and cloddish.
When these two distinct principles meet, there is creation.
In Buddhism (as in Samkhya,) liberation consists in getting rid of the influence of the gross elements, the organs of action and senses, the mind, and the Ego; so as to reach the Awakening and enter the states of the unmanifested/avyakta (which differ slightly among the different Indian philosophies and religious beliefs, but remain, for all of them, in the phenomenal realm of Nature.)
As far as going back to the Self (Purusha,) Buddhism does not seem to be concerned with that.
Understanding the inverse process of creation (liberation) that these philosophical schools (Samkhya, Bhuddism and Yoga) teach, allows people to better understand the process of creation, that is pretty much the same for all the Indian philosophies (including Brahmanism, in its purely religious form.)