All earthly beings have a creator...like this dog and cat right here. One intuitively knows the parents must have existed, even if they aren't here.
Here, we can see a family—two kids, and a mom and dad. These children came from their parents. Then, where are the parents from? Their parents, then their parents have parents...it goes on.
We now arrive at my third argument, the argument from contingency or, "necessary being".
Because we know birth and death, we know that things on Earth have not always existed, just as I haven't always been here, or you, or the dog and cat above me, or the children in my second slide.
Here I am with God, so he can help explaining this.
There must be some thing existing because of its own necessity without relying on anything else—that thing is me. I do not receive my existence from anything else, but I do cause things to exist.
My good friend Aquinas is right. All beings/earthly things are contingent, meaning they rely on outside forces for their existence. We cannot assume that every single thing is contingent—there has to be an original source of causes—that's me, God. The argument from contingency shows how I exist to cause other beings to exist, rather than me also being dependent on a source for my existence.