zero point is a term in cosmology that references no usable energy. The universe being a closed system will eventually run out of energy. This is why we believe it must have a beginning because there is no eternal power source for the universe. It could not be powered for eternity therefore must have had a start.
There must have been a zero point to start from and there will be a zero point at it’s end if God does not intervene.
At the beginning there would have been no mass and no energy. At the end there can be mass but no energy to run it. Meaning the universe would go dark and cold and planets would stop moving.
yes there is a set amount of mass and energy in the universe. Any new starts or planets form from already existing elements and energy.
At the initial zero point we believe God created because things do not create themselves or appear without a cause. The only reasonable explanation is an intelligent, all powerful, all knowing, being started something a zero point.
I hope this helps