I agree with you that other life structures seem quite possible. I don't see the problem. But I'm not a professional biologists.
Still, it seems there are a number of biochemists who believe (or believed) that the structure of earth life could be unique. These people knew a lot more than me. So I wouldn't credit this to arrogance so much as a very complex question, one that doesn't necessarily get easier to solve the most data you get (at least on our scale of data).
Still, it seems there are a number of biochemists who believe (or believed) that the structure of earth life could be unique. These people knew a lot more than me. So I wouldn't credit this to arrogance so much as a very complex question, one that doesn't necessarily get easier to solve the most data you get (at least on our scale of data).