Translation:I am also American.
If you want to link two similar subjects, you use "to" (と)
"I am japanese and also american" would be "Nihonjin 'TO' Amerikajin desu", rather than 'MO'
(You could also begin the sentence with 'watashi ha,' but it's usually implied that you are talking about yourself. Using "i" pronouns too much can be seen as self-absorbed in japanese.
[To repeat the primary sentence here: わたし は 日本人 と アメリカ人 です]
Hopefully this helps. It was fun to explain.
I think I noticed a pattern with the 人 kanji. Is this kanji only used when talking about nationalities? For instance, if instead the translation said "I am also tall," the 人 kanji wouldn't be needed.
Duolingo appears to be following that rule. They have the practice example of わたしも学生です and writing わたしも学生人です would make it wrong, right?
No, it's just the pronoun "I".
です is the verb "be".
わたし = I
も = also/too
アメリカ = America
人 = person
です = am
Japanese verbs don't conjugate the way European verbs do. No matter what the subject is, it will always be です. I'm translating it as "am" here because the subject is "I".
I am also an American.
As in, "You're an American? So am I. Me, too. We're both Americans."
or "I am Japanese, and I am American as well. I claim two nationalities."
As for me, I am an American.
Similar to が but emphasizing that I am the topic of conversation.
I am an American.
A plain statement with no commentary. No reference or comparison to anyone or anything else.
It's too bad there's no way to report that.
わたし (kanji: 私 -- watashi) "I"
も (mo) "also" (in Japanese it's classified as a grammatical particle)
アメリカ (amerika) 人 (jin) -- literally "America-person" or "American"
です (desu, pronounced dess) -- "am" (really just the present-tense of "to be")
is literally "I am an America-person". The 人 is like an agentive suffix. アメリカ人 is how you would say "American" in Japanese.
on the other hand is "I am from America". The しゅっしん is more or less "to be from".
Someone who was born in Japan but moved to the USA and became an American citizen can say
This chart is fairly comprehensive, although it omits the small っ:
The small っ has two different uses: When written before a syllable, it means the next consonant is geminated (pronounced for twice as long). When written after a syllable, it means the previous consonant is pronounced for half as long. Obviously, when it appears in the middle of a word, you need to already be familiar with how the word is pronounced to know which syllable it applies to.
This is a quick-and-dirty list of Japanese particles, but it does not discuss their usage in any depth:
This seems to explain particles a little bit more:
I don't think the Japanese is as ambiguous. If you say 私も学生です (watashi mo gakusei desu) with the も attached to 私, you are saying that I too am a student, in addition to someone else who is also a student. If you're adding additional information about yourself (I'm a part-timer and I'm also a student), you need to use a slightly different form. 学生でもあります (gakusei demo arimasu) means "I am a student (in addition to the other thing I am)".