I don't even know what you are saying here. We know what design by an intelligent agent looks like,
Yeah, I agree. We know what design by
humans looks like.
Humans. Not some divine being, not super-advanced aliens,
humans. And there is nothing in human design that has any parallel to what we see within the cells.
how it is structured, how it functions and how plan and purpose are structured into design.
This statue lacks function, purpose, and, depending on your degree of art snobbery, any sense of "design". And yet, anyone would be capable of telling you what made that, and why they came to that conclusion (humans, because there is nothing else known in nature which produces this kind of purified metal in this quantity).
Meanwhile, on the other end, we have biological mechanisms, and I welcome you, again, to
demonstrate that there was any sort of plan or purpose for them. Or to define what "purpose" even
means in this context.
The fact that we can and do recognize design by intelligent agents we can observe living organisms having those features, structures, systems and functions and recognize them as design.
The only design by intelligent agents we have access to is human design, and human design is not capable of crafting what is present within the cell. At best, you have a bad argument from analogy.