Worst case you can expect AI to become alien, becoming human like is probably one of the better outcomes.
We as humans only have human intelligence to reference what intelligence is, and in doing so we commonly cut off other branches of non human intelligence in our thinking. Human intelligence has increased greatly as our sensor systems have increased their ability to gather data and 'dumb' it down to our innate senses. Now imagine an intelligence that doesn't need the data type conversion? Imagine a global network of sensors feeding a distributed hivemind. Imagine wireless signals just being another kind of sight or hearing.
No, if one can conceive of such aliens, that would be the best case. The worst case is falling back to the understanding of the human, for the reasons you describe.
However, as you point out, one does not need to have any understanding of AI to conceive of what AI can become as natural creatures can theoretically evolve into the same thing. Experts will have already been thinking about what problems might arise if alien life came emerged earth long before AI even existed. AI doesn't change anything.
We as humans only have human intelligence to reference what intelligence is, and in doing so we commonly cut off other branches of non human intelligence in our thinking. Human intelligence has increased greatly as our sensor systems have increased their ability to gather data and 'dumb' it down to our innate senses. Now imagine an intelligence that doesn't need the data type conversion? Imagine a global network of sensors feeding a distributed hivemind. Imagine wireless signals just being another kind of sight or hearing.