Now, I'm no cosmologist and I'm terrible at understanding science but are there good philosophical and scientific reasons to believe that the universe could be eternal/infinite into the past and thus didn't need to have a beginning and thus a God/creator to begin it? Or is an uncreated/beginning-less universe just wishful thinking? Please let me know and for you scientists and sophisticated philosophers out there, can you please explain it to me like I'm 5? I'd really appreciate it lol.
Currently our best understanding is that over 14 billion years ago everything in the universe was contained in something like a small compact singularity. Think of it like an nuclear explosion, how all of the tremendous energy released from a nuclear explosion comes from splitting a tiny atom that can't even be seen with the naked eye. So over 14 billion years ago this singularity started to expand/explode in what we call the Big Bang. That's when the universe started existing in its current form. At this point that's all we can say with any degree of certainty.
Did the singularity always exist? That's a tough question, since our concept of time didn't exist prior to the Big Bang, but the honest answer is we don't know. IF there's some sort of 'cosmic time' beyond the space/time continuum that we currently exist in, we have no way of knowing if the singularity always existed in some form or not.
What sparked the Big Bang? Again, we don't have enough information to provide an answer. Theists will claim that it was some creator god that caused it, but there's no evidence to back it up. It could just as easily be that singularities expanding in such fashion is simply what singularities naturally do.
So no, an uncreated/beginning less universe isn't just wishful thinking. In fact, considering that the our entire understanding of the current universe is based on it being a natural process, it could be said that it's insisting that some creator being had to have intervened to spark the expansion instead of it being a natural occurrence that's closer to wishful thinking.