No, it was never intended as an ontological statement, sunyata is framed in terms of the 5 aggregates of human experience.
Sunyata was not (officially) part of the teaching of the 5 aggregates. It was a Mahayana teaching:
As recorded in the Anatta-lakkhana Sutta of the
Pali Tipitaka (Samyutta Nikaya 22:59), the Buddha taught that these five "parts," including our consciousness, are not "self." They are impermanent, and clinging to them as if they were the permanent "me" gives rise to greed and hate, and to the craving that is the source of suffering (see the
Four Noble Truths).
The teaching in the Anatta-lakkhana Sutta is called "
anatta," sometimes translated "no self" or "not self." This basic teaching is accepted in all schools of Buddhism, including
Theravada. Anatta is a refutation of the Hindu belief in
atman -- a soul; an immortal essence of self.
But
Mahayana Buddhism goes further than Theravada, and teaches that
all phenomena are without self-essence. This is sunyata.
Sunyata is often misunderstood to mean that nothing exists. This is not so. Instead, it tells us that there
is existence, but that phenomena are empty of
svabhava, a Sanskrit word that means self-nature, intrinsic nature, essence, or "own being."
Although we may not be conscious of it, we tend to think of things as having some essential nature that makes it what it is. So, we look at an assemblage of metal and plastic and call it a "toaster." But "toaster" is just an identity we project onto a phenomenon. There is no inherent toaster essence inhabiting the metal and plastic.
Sunyata - The Perfection of Wisdom in Buddhism
A chariot is used as a metaphor for emptiness to include all things beyond just man.
Once again, the fact that anatta means 'no-self' can only point to a universal consciousness. Do you understand how this is so?