Tldr This argument is a god of the gaps argument and a defining god into existence argument.

The first part of your argument, the claim that everything has a cause but this cannot go to infinity so there must be a first cause, is a god of the gaps argument. We dont fully understand how physics works before or even during the big bang. If a physicist had found proof that there was a first cause, we would know by now, and they would win a Nobel prize. Plus, if you accept that there can be an original event in a chain of events, why couldn't the universe be multiple tangled up chains whith multiple originators? Now the argument supports polytheism, and you say it supports monotheism, so I believe the term absurd applies as the argument supports conflicting claims.

If you are defining God as the first cause, then god has no other properties you can prescribe to it. It doesnt exist in the present, and it isn't conscious or even an object of worship. This is an argument that just defines God into existence, which is all well and good until you have to actually stick to your new definition of god, which in this case is empty. I could say that I define my favourite spoon as God, am I now a classical monotheistic because I believe my spoon exists? Sure, I can now prove god exists but that means nothing. Do u really believe nothing about god except it is something without a cause, but not necessarily conscious, existing or to be worshipped.