one vs ones ('the first one' or 'the first ones')

English as a Second Language English Vocabulary, Grammar and Idioms
1

The first one or the first ones?

what are the differences?

thanks in advance

2

Hi,

The first one is singular as in: I have never read any of the books by this writer before and this is the first one I have read.

The first ones is plural as in: We were the first ones to arrive at the party.

Alan