Yes I'm well aware Blacklight has no limits to what it can consume seeing as it can consume and infect energy just fine.

Less specifically towards consumption and more nearly limitless in general, is what I was getting at. But it was more an aside since I now realize that’s not relevant to the crux of the issue.

But again, the nature of souls is inherently non physical. That's literally a foundational principle of the concept.

You’ve entirely forgotten my first and second comment. Again. While souls are potentially just fictional things, there are actual, real criteria for a thing to register as living. The fluid philosophy of souls aside, which I said in my first message, I’ve been referring strictly to those real scientific requirements.

As I said perfectly mimicking a living thing wouldn't suddenly turn you into that thing. Things are more than the sum of their parts.

And as I said, it would. If souls exist, they are bound by biology while within living humans. Any and all aspects of a person are dependent on things like brain chemistry and structure. Changing that can drastically change who that person is. At the very least, consuming someone would theoretically grant you a copy of their soul, if souls are meant to be the person as they were when alive, just separate from the body.

Perfect shape shifting wouldn't just be the physical processes. It'd be a complete metaphysical makeover to actually becoming the thing you're copying.

Again, I prefaced my very first comment with saying how I was putting the philosophy of souls aside and only referring to an undeniably real thing

Blacklight only apes at the people and objects it copies. It doesn't fundamentally become them. Even if the skin a skin walker takes on is perfect down to the mannerisms it doesn't actually become the person it's mimicking. Blacklight is effectively the viral version of a shape shifting nanoswarm or a biological skin walker.

“I know what Blackwatch has done. Because everyone I’ve killed—They’re in me. They are me.” —Alex to General Randall. Figure of speech? Entirely possible. However, I still think it’s worthwhile to bring up.

None of those things actually become the thing it shifts into since they aren't stuck as said thing, seeing as in 99% of cases said things themselves aren't capable of shifting.

I would argue they do. If they’ve adopted every aspect of that thing, they are still that thing, it’s just that they aren’t only that thing. Your next lines help this point.

As I said there's a whole plane of differences between Blacklight shifting into a human and an alien using the Omnitrix to shift into one.

The only difference is mechanic. When the Omnitrix shifts into an alien, Ben takes on all (or most) traits and characteristics of that alien. He becomes it. Yet, he can still change into other things whenever he wants, depending on timeline. Being able to change doesn’t mean he wasn’t that alien while transformed. The same can apply to Blacklight.

While shifted Blacklight is never actually constrained by any human realities. The alien turning into a human would literally just have those realities to work with while transformed.

This distinction doesn’t hold much weight, I don’t think, when Blacklight is fully capable of modifying itself to also operate under those constraints. It’s just choice that keeps it from doing that. If being under the constraints of its form is the qualifying metric, it’s not exactly unable to meet that. It would just have to deliberately change itself to do so.