The issue here really is what you mean by 'plausible'
What is worked out in mathematics to very fine levels of detail, complete with predictions that accurately match the observable universe and reviewed by the world's scientific community, is – by you – dismissed as implausible. Even though you demonstrably don't understand the science.
Instead you offer us an imaginary being who 'caused' the universe. You offer no evidence for that, except a book put together by multiple authors over 2000 years ago, which – you claim – offers a better explanation.
You are entitled to that view; just as you are entitled to claim that the moon is made of green cheese.
Your questions pertaining to the nature of nothing show that you simply don't understand quantum fluctuations.
A particle and its anti-particle amount to nothing. Literally, nothing. In this sense 'nothing' can spontaneously give rise to a particle and its anti-particle.
This is the quantum foam that you so easily dismiss as implausible, despite the fact that much greater minds than mine or yours have demonstrated that not only is this possible, but it frequently happens in 'real life', and have worked out detailed explanations of how and under what conditions it can happen.
There really is no point in seeking to educate you in this area, because you choose to dismiss the mathematics, research and calculations that demonstrate the validity of the scientific model.
That model successfully predicts all kinds of observable evidence. It is testable by those who have the tools to test it. Those tests have shown that the model is succesful.
Your model (God) does no such thing. You assert that God pre-existed the universe and is the first cause of the universe. You present no evidence (except Biblical stories) ; you make no predictions based on that theory and you fail to show how your theory might be tested or falsified.
Theland, this is not an argument you can win, when we stick to the rules of science and logic. Science is based on observable evidence.
Your beliefs are based on faith. A deliberate jump into the unknown and unknowable.
The two are not incompatible, except when you start to assert that your faith brings better insights than science into observable facts.
Science can deal in facts, theories, evidence and mathematics.
Faith can deal in mystery and mysticsm; allegories and belief. There are insights in that.
But faith won't bring insights into star formation; gravity; dark matter; quantum mechanics or relativity.
When you use the language of faith to discuss those things, you make yourself look silly, which is why you get negative comments on here when you try to do that.
Keep your faith; love your God; but if you try to explain cosmology using faith alone, you will continue to attract mockery; bth on this site and elsewhere.