BE, HAVE, DO

Would you say you are identical — yet two people, every day — one loves books, the other music; or, one loves cars, the other sports? This is what things would have to be with you, if you give credit to this notorious tale of the auxiliary verb.

Those "yous" would look and sound exactly the same. "Yous" would differ only in doing things. If you would be having cereal, I am afraid this would add up to a yet another identity, all to become difficult to sum up, after all.


TALK ENGLISH, AUXILIARY VERBS;
CLICK TO ENLARGE.
TALK ENGLISH.

Let us read the grammar advice.
"An auxiliary verb helps the main (full) verb and is also called a "helping verb." With auxiliary verbs, you can write sentences in different tenses, moods, or voices. Auxiliary verbs are: be, do, have, will, shall, would, should, can, could, may, might, must, ought, etc."

It follows from the above directly, that there is a verb to be which means existence. Another verb, which looks and sounds exactly to be as well, is a "helping verb".

The "helping" be, have, or do mean nothing, literally niente, to help the point with a little bit of Italian, should the predilection for assistance be spreading, among English language elements. May the diligent learner listen or hear out: being someone, doing or having a thing, become not it at all, once the forms turn out to be the helping clones.
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Let Granny think about times that were before. I do not mean granny olden times, because these to talk here were much before. We only do not need to picture the cave people ancestry to the English language, for them.

The verb to be can work as an auxiliary in the Progressive, or in the Passive. Today, tales as tall as the one above would tell the verb to be has not even a little bit of being to it, in phrases as
He is sleeping.

The word sense is, however and more or less, He is asleep.

This is the way the Progressive evolved. People or things were in a condition or state, or in a course of doing something, and to describe this, the verbal phrase became expanded. The times were the Middle Ages, in approximation. We can read about this here,
https://www.uni-due.de/SHE/SHE_Middle_English.htm#change

Well, and this would be the conclusion, for today. All words have more than one meaning, and there are verbs that can work as auxiliaries. The auxiliary is a role or function a verb can have, it is not a distinct type of a word.