Any attempt to do that is fallacious. Arguing that the universe came into existence and thus requires an immaterial cause is not the same as arguing that a deity was the cause.
Immaterial? That's a rash assumption. Kind of like saying it was "supernatural". I am very ware of that fallacious reasoning, and can't think of another discussion of this topic I've been in where the other person wasn't arguing for a deity. Are you sure you're not motivated similarly?
You asked two different questions here.
1. Weather "beginning to exist" is a meaningful concept for human beings, which it is. and,
That is not at all what I asked. If I had cut off that sentence after the word "humans" then it would be, but I did not cut off my sentence at that point.
2. Weather "Beginning to exist" actually occurs in nature. which it does..... sort of.
Nope. In no way does "Beginning to exist" occur in nature. It occurs in our language about nature. "Beginning to exist" is a totally alien concept in nature. Which brings up the question of why it's our go-to explantion for anything at all.
Everything that we see around us is an effect requiring a cause, but the same might not apply (and, I think, doesn't apply) to that which those effects are made of. I did not exist before I was conceived but that which I am made of did.
The idea of "you" is an arbitrary, human-created distinction. It began to exist in the minds of humans, not in nature. Nature doesn't care what you call it.
The question yet to be answered is weather or not the big bang was an effect. The jury is out on that, but there is some reason to think that the answer is no.
Is that reason a physical one, or one that relies on our human biases, like your "I began to exist" thing?
It depends on weather the cosmos requires a cause. I like to avoid begging the question and so I'm more comfortable assuming that the cosmos is eternal and everlasting, did not come into existence and will not pass away.
Again: What does it even mean that something comes into existence? Why do we consider the idea meaningful? It's not in evidence anywhere in our surroundings; it is a product of our biases and language, of symbols and labels.
To discover what happened at the instant of the big bang? Yes, they are.
That is not what you said. You said they were doing this:
But, my point here was in answer to the question of why God is said to be causeless. The answer is, because scientists and philosophers in the past who proceeded from he assumption that the world is an effect, needed to posit a cause that was its self uncaused to keep their brains from hurting.
And trying to discover "such a cause". They aren't trying to discover a first-cause. They are trying to discover a cause - at least, the responsible ones are. Big difference in terms of assumptions being brought to the table.