1. Why should there be indefinite articles As and shouldn't be there the definite articles Thes?
Jenny was a most lovable person.
She is a most beautiful person.
You gave me a correct answer.
Because the writer doesn't want to emphasize
these are the absolute best in each respect (the most lovable,
beautiful, correct), but one of the many (lovable, beautiful, correct)
persons or answers. The meaning of "a most" is "very" in the above.
Compare:
a most lovable person = a very lovable person
the most lovable person = the person which
is the best (the utmost) in terms of being lovable (in terms of "love-ability") from
all those whom I'm considering in this setting