Imagine you’re walking along a beach one day and you find God lying in the sand?

Yes, God must have had a creator. Any entity as complex as God could not have spontaneously appeared out of thin air. It would have to be planned out methodically in advance.

This is why when atheists say to me, "If God created the universe, then who created God?", I respond "Why, another God of course, ad infinitum."

God says, "I am." God was always here, and always will be until the end of time. Remember that God is not a finite being like ourselves, rather a being higher than ourselves. Here is another point. How can a lower being understand something higher than us? Animals cannot understand humans. (You might argue that your dog can, infact, understand you, but that is by repetitive behavior or by manipulation) Humans han't even understand himself! One minute you are feeling happy, then another you can feeling down in the dumps.

Does God have to have a creator? God is not an object of design, He was always there!

How would I know that this person is a God in the first place?

Is he wearing a robe? He might have escape from an insane asylum.

I would try to get him back in the water

I would ask him for my three free wishes.

God isn't a physical being...