What creates and maintains the immortality? Does it make any sense?

Whenever there's a ludicrous premise, like 'immortality' or 'toys are secretly alive', I have questions. Oh, SO many questions.

Even putting aside all the things this movie conveniently fails to explain, most of the 'why'-type stuff, there are still the 'how'-things.

For example, how do their muscles work? Seriously, how do muscles of an immortal function? They can't be the same as 'regular people', because any regular people can die from a muscle wound, blood loss, infection and so on. You can get arm pain that lasts the rest of your incarnation, your joints can malfunction, become loose, get damaged, injured and so on.

Can an immortal suffer a similar injury? What use is pain to them, if they can't die? I have asked before, could they be hacked to be just the head and a bit of torso, as long as they have their full neck and still 'not die'? Could they live as a brain in a jar with enough spine? What dictates when and how they die, and what maintains their immortality?

We have been shown them to 'not drown' deep in the water, but yet blow out air bubbles. Do they need to breathe? If so, why wouldn't they drown? How can their bodies work inside water (I refuse to say 'UNDER', because it makes no sense), if their muscles need oxygen, and thus, they need to have lungs to get and process that oxygen, and thus need to breathe, and thus, can drown?

Their muscles, therefore, can NOT work like regular people. Are they made of a different substance (if so, what, and how? Are their bodies made out of metal or some kind of plastic fiber?), or is there some kind of magic involved in maintaining their 'immortality'? Muscles that don't need blood, oxygen, etc., that yet still function like regular muscles - how does THAT work?

If they are maintained 'magically', then who maintains the magic? Is it automated, and if so, how can that be, and .. you see how many questions 'immortality' immediately raises?

We've seen these people fall from great heights and not die. Fine. But we've also seen them bleed, get injured and damaged, and it absolutely makes no sense that the villain gets a throat cut but doesn't die, and yet the cut heals, but not completely.. again a movie trying to have it both ways.

So how does this 'fall from a great height' work - a normal individual would probably take a lot of damage, internal bleeding, bones fracturing or breaking, organ damage and failure, concussion, brain damage, and so on and so forth - not to mention tissues, joints, and other injuries like that.

But these people keep fighting after such a fall. Does this make any sense?

I get it that they won't -DIE-, but this movie does a lousy job in explaining what else that entails. Do they also not get damaged or internal bleeding? Do their bodies need blood, or is it just for show? Can they be mangled to a pulp and keep living as long as the neck remains intact?

I've asked this kind of stuff before - do their limbs grow back if you cut them off?

It's not enough that they're immortal, if they can be paralyzed or something. 'We must fight blah' - you must? Who says you must? 'Holy ground.. no one will violate.. it's a tradition' - how can you KNOW no one will violate that rule, and why can you know it? Who created the rule, who made that tradition, and why can you be so sure that the vilest villain in movie history will respect tradition, even though he's clearly ready to mutilate everything else? Why does a tradition hold such power?

Are there consequences for violating this tradition? What constitutes a 'holy land'? Anything any cult or religion member decrees as such, or is there some kind of ritual involved? Just because someone builds a building and calls it a 'church', doesn't mean the land is HOLY (though planets are holy by default, being Creations of the Divine, but maybe the writers didn't think this far).

So, what maintains this 'immortality' so much that these people don't seem to need functioning hearts or other organs, blood, oxygen, or muscles that work the same as other people's..? What heals their wounds, and why is THAT part of it? Shouldn't they be able to be immortal without having to heal the wounds, because their bodies are obviously completely different, if they can function without oxygen?

What I mean is, if a regular body is stabbed in the heart, it can't go on maintaining life within it. Death will be imminent. But these people can be stabbed all day long, and not experience death, so their bodies do not respond or function like everyone else's, so they don't really need a functioning heart (or they couldn't be immortal).

I am really trying to understand WHAT makes them immortal - is it some kind of Cosmic Law or Divine Decree that keeps magically replenishing them so they can't die, or some kind of 'Karmic' rule that keeps them out of lethal situations, or is it some kind of magic that some wacky Wizard cast as a spell on them, or do they come from another planet, or or or..??