All I'm claiming is that before whatever happened, there must have been a mathematical structure that allowed it to happen following certain physical laws. That's just a fact. So these mathematical laws exist before anything. This implies a realm that's not physical. Anything that is contingent such as all material things (why is there anything at all?) must have a prior cause - and that's an assumption of science.
All theories presuppose these mathematical structures.
That is, even if the current big bang is just one in a series of several, or however else you try to explain existence, you have to presuppose the mathematical structure that forces it to follow certain physical laws.
I also don't think you fully understand inflation and why it's been proposed but I'll ignore it since it's not useful for the conversation. Also read up on the Borde-Guth-Vilenkin theorem as it basically proves that a beginning is necessary.
In addition, note that right now it seems almost certain that the universe had a beginning and any other explanation is not evidence based.