You go on to say that we know the above to be false, but your argument is unconvincing. Bertrand Russell was not basing his argument entirely on the law of conservation of matter and energy. He is asserting that the Universe doesn't need a first cause in order to exist because the non-existence of the universe is logically impossible.

A clearer definition of non-existence is required. When people imagine non-existence, the usually imagine a void, and area with no particles or interactions. In truth, since the big bang, even voids have field potentialities making even empty space not empty. Non-existence is not the same as a void. Non-existence would be the absence of all particles, energies, fields, space and time.

A state of non-existence would not record the passing of time. Time is a measure of change, and there is no change of any kind in a state of non-existence. There is nothing (literally no thing) to measure the passing of time against. We don't have the orderly decay of atomic nuclei or any other period feature to measure. We have nothing.

If i understand your argument correctly, you would say that God would be aware of non-existence, and God's awareness alone would be sufficient to mark the passing of time. Good luck testing that one.

"Something or Someone has to be responsible for existence."

Not if the state of non-existence is a logical impossibility.

If something or someone would not have created the universe, who would have known it?

imagine your pre-creation state of non-existence. God is mulling around the idea of creating something, but he hasn't decided yet. Time is passing while God is considering his decision, and in the end, God decided against creating the universe.

Who would know that God did that?

Let's say God later reconsidered his idea. After more internal deliberation (let's fully anthropomorphise God), God decides he is going to create the Universe.

How long did God hold existence in abeyance?

How would you measure the time between when God first had the idea of creating a Universe and actually doing it?

If the last several questions seem like nonsense, rest assured they are indeed silly ideas, but they are natural extensions of the idea that there is a God who exists outside of space and time and is needed to create the whole thing.

God isn't necessary to create existence. The logical impossibility of non-existence is all that's required.