You see, if the difference is quantitative or qualitative then "being a person" seems to only mean "more of ...something else...". It would be justified to critique the idea that 99% personhood is not sufficient to require 1% or moral value. This brings me back to point 2 arguments.
That's a quantitative difference, not a qualitative one. I don't see why we can't leave that on the table, but I also just generally think it's nigh impossible to distance yourself from any and all quantitative and qualitative differences.
If different persons get their value from being part of a category rather than having certain traits, then we could justly apply equal value to persons without being inconsistent.
I'm seriously just interested to understand what you mean by "category." How do we establish what is and is not part of a category without establishing that there are quantitative and/or qualitative differences between that category and other categories? What do you use if not them to isolate those that are deserving of human rights from those that are not? Without seeing that, I can't say whether this is something that's even possible to do, let alone whether it's an appropriate boundary to accept to this discussion.
Limiting the debate seems not to be a problem - we are far too good at getting of track XD
Technically, this isn't even the debate, as far as I'm aware. It's just setting the stage for what the debate would be, or maybe narrowing in on said debate. We're definitely going off on a bit of a tangent, but like I said before, I think it's important to land solidly on this before we proceed.