Mainly, what was there before the big bang?

Nothing.

Literally nothing. Not time. Not space. Not anything in our normal range of understanding.

By the very nature of our brains and perceptions, we are confined to thinking of the universe in the three dimensional framework that we personally observe.

It is not easy for us to visualize a state of existence that is so far removed from our day to day observations of what we consider to be reality.

tanstaafl.