Translation:I am British.
But you have to remember, Japanese isn't culturally connected Great Britain or the UK. As important as the distinction might be in English-speaking minds (who are familiar with the politics and history involved), Japanese is simply trying to refer to people from another country. The language doesn't distinguish because (in day-to-day function) it doesn't need to.
That is not actully true. While Japanese do construct nationalities by placing 人 next to a country name, that is far from being its most important use. So calling it a "nationality particle" will confuse people when they see it in all sorts of environments where it is not indicating nationality, like in the word 恩人【おんじん】"benefactor; patron" or in the word 管理人【かんりにん】 "janitor; manager."
I bet they say something different for Ireland. Also, check this out: https://www.quora.com/Do-the-Irish-in-Northern-Ireland-consider-themselves-Irish-or-British Wow, people born in Northern Ireland can have dual citizenship if they wish.
Also, even though Great Britain is the biggest island, Ireland used to be one of what was called “the British Isles.” https://en.wikipedia.org/wiki/British_Isles
イギリス means UK, but the character that comes right after it means "person." So you have [UK person am] “I am a British person.” Perhaps they might allow “I am a person from the UK.”
“I am from the UK.” already has two different Japanese sentences already, both of which use a different verb than here.
イギリス DOES means the United Kingdom. But it can also be used to refer to England (to be specific you could use イングランド). 「イギリス人です」 can be translated, therefore, as both "I'm British" or "I'm English", but "I'm British" is the standard translation. https://en.wiktionary.org/wiki/%E3%82%A4%E3%82%AE%E3%83%AA%E3%82%B9#Japanese https://en.wiktionary.org/wiki/%E3%82%A4%E3%82%AE%E3%83%AA%E3%82%B9%E4%BA%BA#Japanese
人 means "person" and is used as a suffix to describe a person - their nationality (as well as race)
出身 means "origin" and is used to describe a location - the origin, the place you have roots in. (this can be country, town, school, parentage)
日本人 - Japanese
日本出身 - From Japan
フランス人 - French
フランス出身 - From France
アメリカ人 - American
アメリカ出身 - From America
A person's nationality and origin may not always be the same place
Kanji can be pronounced a number of different ways based on context and Duolingo's word-by-word pronunciation method doesn't take this into account, often leading to incorrect readings of Kanji.
人 can be read as both "hito" and "jin," though the correct reading here is "jin."
Not quite. Britain is a geographical area, and is composed of three countries: England, Scotland and Wales. Northern Ireland is on the island of Ireland, but wants to be aligned with Britain. So, The UK is Britain (England, Scotland and Wales) plus Northern Ireland. The people from Northern Ireland call themselves British. Thus although not everyone in the UK is in Britain (because Northern Ireland isn't) everyone in the UK is British. Don't worry - a lot of British people get confused about this as well!
Japanese de-voices certain vowels in certain contexts. "i" and "u" are almost silent when between two voiceless consonants, or follow a voiceless consonant at the end of a word. Thus, "desu" is usually pronounced more like "des," though the "u" IS actually there and can be heard by a trained ear.
I think this just about the difficulty in following rapid speech with an untrained ear. So you are hearing the end of "Britain" run into "person", i.e. what is being said is igirisu jin desu, but you are hearing igiri sujin desu, because there is no pause between words, and the "j" of "jin" is very soft. This happens in English all the time, but a native speaker doesn't usually have any problem, e.g. "It's a nice house" versus "It's an ice house" (part of a joke). Constant exposure to the sounds will help you gradually to make out the distinctions. Hope this answers the query.
It doesn't, but a word can change meaning over time. The Japanese word for "English" came to mean UK or Great Britain and the Japanese for English person came to mean British. So now they have a different word for England and English person adds the word for person to that.
How far can we stretch it? Would they accept "I am a member of the UK." ? I am betting not as they probably have a different word for "member"or even "citizen".
イギリス historically meant "England", "Britain", or "Great Britain" but in recent years it has grown to mean "the U.K." A closer approximation would be United Kingdom-er or someone from the U.K, especially if the context is about countries. You can say "Scotland" or "Wales" without mentioning the U.K. in general but be prepared for questions.