"I am from Tokyo."
I'm still learning, and i was having a surprisingly hard time finding a detailed explanation, but from what i can gather... 出身 is a no-adjective (meaning birthplace or origin), and the の can be omitted without any loss of clarity.
this sentence could be slightly rewritten in a more beginner friendly way as 東京の出身です, which would literally be translated as something like "it is a Tokyo origin" and the implied subject of the sentence is "me" or "my origin"
anybody with more experience please let me know if I'm misunderstanding
I think you have a good understanding of it, I would just add that 東京出身 is more commonly used in my experience.
This wanikani thread has some good insights-
One user asked a Japanese friend about using 東京の出身です instead of 東京出身です:
Just less common she says.
Another user says:
Just like in English, sometimes you can just smash nouns together to make longer nouns. That’s why the JLPT is not the 日本語の能力の試験.
Whether or not this works is something that is based more on intuition than written rules.
In English, if you take a compound noun and make it into separate words (i.g. you say "board of keys" instead of "keyboard") it often sounds strange. If you say "light of the moon" instead of "moonlight", it doesn't necessarily sound strange, but it might sound more poetic or give a different mood/feeling to your sentence. That's what using 東京の出身 (toukyou no shusshin) versus using 東京出身 (toukyou shusshin) feels like to me. 東京の出身 is of course not wrong, it's just more natural to use the compound noun 東京出身.
I think because that can only be in response to the question 「どこから来ましたか?」。 in this instance you'd have to say 「東京から来ました。」 if there was not preceding question to pull the contexts. 「とうきょうから」 is only a phrase, its missing a verb, which is vital in this instance to understand meaning out of context. Even still, 「東京出身です。」 is more straightforward because you know that you're talking about a hometown, not just that you literally just came from tokyo.
I'm not a native speaker (but I did study for 4 years and lived in Japan for a couple of months), so I might not be able to articulate why this is as well as someone else, but you would have to use the past tense of 来ます(きます) i.e. 来ました(きました) instead of しゅっしんです if you wanted to word it as such (note that you've got a 'su' rather than a 'shu').
However, the question does not accept: -とうきょうからきました。(did not test, but assuming 来ました not accepted) -東京しゅっしんです。 -とうきょう出身です。
Which I feel like it probably should.