Computers / Robots will always be limited.

The brain doesn't really work off electrical switches like a computer. It's a chemical device where neurotransmitters move signals between synapses. A computer a far simpler device.

He's not making an assumption, he taking that from proven factual text. It says in the Bible, thou shalt not create robots with sentience.

"And if god exists, there's absolutely zero evidence of any design."

It's hard to imagine a more asinine assertion than that one. Every organism is a design. A human is a far more complex design than any design humans have ever come up with. Humans are fully autonomous, self-repairing, self-constructing (in accordance to a set of blueprints [DNA], no less), self-fueling, organic machines. There are countless operations being carried out automatically with the cooperation of countless subsystems to make a human work, and this can go on non-stop for up to 120+ years. The average human has about 37.2 trillion cells, which is a number that you can't even comprehend, and each one is a machine unto itself.

"There's tons of evidence for evolution as to why/how we exist."

The evolution narrative contains enough conjecture to sink a battleship. The critical aspects of the narrative have never been demonstrated. We can only demonstrate that evolution (the process itself, not the amoeba-to-man narrative) happens. The narrative that says that a single-celled organism was everyone's (and every critter's) greatest grandfather is pure conjecture, by definition.

How about you explain how animals obtained instincts, and how they survived before obtaining them? Let's just look at hunger for example. How did the first critter that had to consciously decide to eat food know that it had to do so? Furthermore, how did it even know how to implement the process of eating? How did it even know how to swallow, or control any muscles, or any functions at all, for that matter? This knowledge isn't something that can gradually happen, because any critter will die in short order without sustenance, or without the brain knowing how to initiate and regulate the function of the heart and other vital organs.

There's no time for any critter's brain to "learn" all the knowledge it needs to survive, because it would die almost immediately without that knowledge. A "blank slate" brain wouldn't even know how to operate the lungs, therefore it couldn't breathe, which means it would be dead in a few minutes. And even if, like magic, it suddenly gained all that knowledge of how to operate the lungs, heart, etc., in time to survive, its offspring can't inherit acquired knowledge, so it would be a dead end.

There's no way for the evolution narrative to get off the ground. The only way it works is with a variety of fully functioning, basic lifeforms being placed here by someone. The first step would be microrganisms and plant life to create the bottom layer of the food chain, and which would generate and sustain oxygen content in the atmosphere. These lifeforms would evolve to suit their environments as they were designed to do. Then at some later point in time, once the conditions are suitable, you would bring in some more complex lifeforms to add the next layer of the food chain, and so on. I believe that the creation account in Genesis and various other ancient texts are simplified/stylized accounts of this "terraforming" process that someone did here in stages over the course of many years in the distant past.