An upstart; a man newly risen into notice.

a person who has suddenly risen to a higher economic status but has not gained social acceptance of others in that class

characteristic of someone who has risen economically or socially but lacks the social skills appropriate for this new position

Parvenus are people that are relative newcomers to a socioeconomic class. The word derives from the French language; it is the past participle of the verb parvenir (to reach or arrive).

of or characteristic of a parvenu