During my first brain tumor surgery, I just saw myself from around 10 feet apart and 10 feet above my operation table. I could hear the voice of doctors & nurses operating on my body. I remembered that top view and voices for many days after the surgery. I was able to recognize the doctor later with the voice that I heard that time.

I’ve witnessed and assisted with many deaths. A lot of people experience hallucinations before death. Their experiences also are highly dependent on culture. I have not experienced anything to suggest any supernatural involvement.

I can see many ways to aproach this question. on the physical sense, as if its a halucination, many say that when we die our brain produces a bunch of dMT and what we experience is basically one of the strongest halucinogens that exist and if its anything like recreational use of DMT, which I've done a few times, it can induce what I call "eureka experience" which is the illusion of thinking you suddenly understand the meaning of life. but if you write it down and read it the next day it can sometimes be mostly non-sense. the eurika experience is a sensation that feels like information. that "now I understand" sensation but without rationality. just like how non-sense in dreams seem like just normal when you're in it.
another way to look at it, lets say " spiritual" way, is that some say we are eternal beings and we come to earth to experience new things but to make the experience really intense and meaningful we intentionally leave our knowledge behind in the same way as to trully experience a movie you have to forget that its a movie, if you watch the movie and see actors and special effects you will not experience it the way it was meant to be experienced.
on a more personal note I almost drowned once and just when I gave up and accepted I was going to die I had the sensation of a window of light apearing and telling that if I die its going to be ok because they will take care of me.
to come back to the DMT experience, its a very common effect that people meet "teachers" that tell them about important life lessons or big theories about the meaning of life. during such an experience a teacher, wheather a halucination or not, told me some important stuff about life and ended with " but now the lesson is over and you have to go " and just like that I was back and completely lucid and normal but feeling happy and at peace.
note: I am in no way suggesting that someone should try this, it could warp your mind forever.

Once the consciousness escapes, even for a short while the materially and time constrained realm of this place, it is probable this enables something akin to limitless understanding. With access to our memories, ofcourse.

It takes time here, even if a very small amount, to process a thought here. Just imagine if one could accomplish in no time at all thoughts equivalent to a hundred years of meditation after shedding this, as Shakespeare put it, "this mortal coil"

Being told to go back doesn't seem that unlikely. Maybe that's one of a set of selected options we choose before being born.

Checking the box to be impelled to return if a premature ejection occurrs during life would seem to be an important choice to prepare for. If in fact, we do choose to be born.

Changes in brain chemistry due to oxygen depravation can induce similar experiences. (DMT) cited below is a good example.
If the subject is revived they will often 'remember' common visions, sounds and profound early memories etc.
I'm a firm believer that when you're dead that's it, therefore make the most of this random miracle of life you've been given.

I'm on your side on this. That being said, who am I to really question someone's personal experience?

The fact of the matter is, with the current state of the scientific community, we have no way of knowing whether near-death experiences are genuine insights into the afterlife or the hallucinations of a dying brain. This is unfortunate, as I should like to finally live in a world where there is hard evidence for life after death.