Albert Einstein said: I want to know how God created this universe.
All the rest are just details.

When matter was created at the beginning of the universe I believe it
started to move due to its own force. Its freefall imediately set it
into motion. In other words: there was no absolute rest as Einstein
alluded to.

The original expansion was inflation which quickly spread matter apart
so that gravity would not recollapse the Big Bang in a Big Fall.

Mitch Raemsch Twice Nobel Laureate 2008