As for existence, it is what it is.

Existence is tedious and a lot of work for a couple seconds of pleasure every now and then.

If God created everything there can't be another being that didn't create anything because God would have had to create him first.

Did God create himself? Or did he already exist? If he did, what is time? Is time a cycle, or a line?

The idea of selfcreation? In religion the timeless divinity and in science the Universe that spawned itself. Foreign to neither.

I think he just existed but I'm not 100% sure since I haven't meet him yet. And I see time as a line.

Existence is simply consciousness or a sense of awareness regardless if you believe in a god or not. Animal and machine can also become sentient or exist in the same sense as humans. Of course, this is just my opinion.

Pretty logical opinion to be honest. Absolutely no reason to believe machines won't understand their own existence in time. I'm sure the human brain is being studied and as time goes by the logic patterns of the human mind will be mapped and replicated artificially. It's certainly nothing incredible to expect that. DNA itself holds the design instructions.

We might think differently about ourselves when the human mind is so analysed that AI can even predict our responses.

Maybe in 200 years we will be playing Fallout 125 and the opponents in the game actually have equal intelligence to the person playing the game. The morality and ethics of that would be quite controversial especially as that simulated mind is constantly put through trauma and death and only actually existing when you play the game which completely trivialises their existence.

Existence is defined by a perspective. It is a purely relative notion.

It will definitely force us to rethink morality and ethics. We'll likely debate it over centuries. With AI, I think we'll limit the intelligence and the ability to think beyond its purpose to prevent self-awareness or becoming conscious.