All observations and thoughts point to the following results:
a) The root of all cannot be matter, since matter does not account for inner/psychic phenomena and experience/consciousness.
b) The root of all cannot be an idea, since an idea cannot be a substratum; how can an idea be processed, exist on its own, without matter or substance?
All inquiries, philosophical, theological, logical, point to similar antinomies. Infinite regress, acausal cause, first unmoved mover, the thing we cannot comprehend and many more.
The most certain conclusion leveraging our current knowledge is that the root of existence is a PARADOX relative to our current understanding and reasoning. We can never reach it with classical logic, Aristotelian syllogisms, current mathematics etc.