Was the 20th century a century of prgress?

We are in the 21st Century.

It illustrated the desires, practices, culture and style of the day

Century is a time period of 100 years (stemming from the Latin cent meaning 100).Centuary is of or pertaining to Centaurs the mythical creatures (half man, half horse).

it went from 1900 to 1999 it was a span of 100 years which is also known as a century.

Different people would interpret this differently, and there is no generally accepted rule (as the fact that you have asked the question indicates). Of the two suggestions you offer, I would prefer...