I learned ancient Greek at school 35 years ago. Amazing how words come back out of the subconscious after all that time. I tend to know the meaning of words that I have never seen before. Although the pronunciation has changed a lot it is not so different. Great course guys. Loving it so far. Well done.
So, is the given sentence then more of a teaching construct, designed to relate the indefinite article in English and Greek? I'm wondering if ένα is normally used more often in the sense of "one", a definite number, rather than just as an indefinite article. Or is the naturalness of the feel a rather less specific kind of thing?
Ένα is used both as an indefinite article (a/an) and a number (one). The given sentence is grammatically and syntactically correct but it sounds kinda robotic. In this kind of short sentences, [ (subject +) verb είμαι + predicative ] native speakers do not use the indefinite article. "Είμαι άνθρωπος", "Είναι ζώο", "(Ο σκύλος) είναι κατοικίδιο", etc.