Do all native speakers know that "Good morning" is "I wish you a good morning"?

yeah, i think every native speaker, even if just subconsciously, is aware of the rhetorical device called ellipsis

We understand that ‘good morning’, ‘good evening’, ‘happy birthday’, ‘merry Christmas’ and so on are all wishing the person a good/happy/merry whatever, yes. As another commenter said, what else could we think it means?

What else would it mean? (Not to start [quoting Gandalf](https://www.goodreads.com/quotes/14559-good-morning-said-bilbo-and-he-meant-it-the-sun) or anything…) I feel like that's the only interpretation I've ever given the phrase. Just as "good night" means "have a good night".

No one understands it to mean "this morning is good" if that's what you're asking. "Good morning to you" is a longer version that no native speaker thinks means something different from the shortened version. Either way, there are plenty of phrases in many languages that lose their original meaning. Good-bye (and bye) is derived from an older form of English's "(may) God be with you." Though it's lost its religious meaning, its purpose is the same. Doesn't matter.

No. Native speakers may or may not believe it is short for a longer phrase. It’s a pleasantry with no meaning.

I think everyone knows what the original meaning is but, in reality, it's just a polite way to greet someone in the morning. You're not really, sincerely, hoping that that person has a good morning every time you say it.

We do—lol. Why wouldn’t we?

I think "I wish" etc. expressions hidden the good/happy/best like sentences. As an Turkish native speaker, we construct the sentences as you stated. Maybe, it is seen unnecessary.

To quote a man well versed in language: https://youtu.be/RtnoK-kf3uc?si=4Le7ZJg9prjbYiYv

We aren't consciously aware of the full meaning when we use it (because it's a mundane social reflex which doesn't require deep thought), but it's easy to infer.

It's just a greeting used in the first half of the day. Not more complicated than that.

Yes, but we also use it as a greeting, the meaning of which beyond the social protocol is often not considered.

if you asked them what it actually means, they would probably be able to figure it out, but a lot of words or phrases lose their original meaning. When people say "Goodbye", they don't mean "God Be With You", they mean "I am acknowledging that this interaction is ending" When people say "Hey, 'sup", they don't mean "What is up?" they mean "I am casually acknowledging your presence. When people say "Good morning", they don't mean "I hope that your morning is pleasant", they mean "I am acknowledging this social interaction, which is taking place before noon". When people say "How do you do", they don't mean "What's happening with you?", they mean "I am acknowledging your presence in a way that I've been taught is 'proper', whatever that means (the 'correct' response to "how do you do" is "how do you do". Similarly, if you say to someone "my cat just died" and they respond with "I'm sorry", they don't mean "I apologise for my actions", they mean "I am expressing that I acknowledge your misfortune, and I take no pleasure in your sadness". This is what I've figured out as a native english speaker who is autistic, because I've learned that there's often a big difference between what people say and what they mean.

Yes, of course we do. As people have been saying, it is clear that it means that and there isn't anything else it could mean. It is used as a greeting and to wish someone to have a good morning.. On a separate note, never apologise for the quality of your English. You are a learner. You are not expected to have perfect English and there is nothing wrong with not having perfect English. We could understand your question perfectly. Keep up the good work.

In German, "Guten Morgen" (good morning) is a shortened form of "Ich wünsche dir/Ihnen einen guten Morgen" (I wish you a good morning). Even in the short form, the inflected form "guten" (with the -en ending) clearly shows it's affected by an implicit verb and is in accusative case. This grammatical marker provides clear evidence of the longer underlying phrase. In English, since adjectives don't change form based on their grammatical role, we can't tell from "good morning" alone whether it's a shortened form of "I wish you a good morning" or just a standalone phrase. The lack of morphological marking makes the historical derivation less obvious in English. It's reasonable to hypothesize that "good morning" could have originated from a longer form similar to German, even though English no longer shows grammatical evidence of this through inflection. Reasonable but not enough.

"What do you mean?" Gandalf said. "Do you wish me a good morning, or mean that it is a good morning whether I want it or not; or that you feel good this morning; or that it is a morning to be good on?" "All of them at once," said Bilbo. "And a very fine morning for a pipe of tobacco out of doors, into the bargain."

Yes

Yes, we know. Also, I rarely see native speakers say “goodmorning” without a space between the words. It seems to be popular with certain ESL groups, though.

I don’t know what you’re suggesting. Are you suggesting that good morning is most definitely short for “I wish you a good morning” ? If that’s what you’re suggesting AND that is true (I don’t know it is) then no - not every native speaker knows this.

short answer: no they do not.