Question

how did most people in Europe dress before the 18th century

Answer 1

Before 18th century the European dress code was a bit peculiar. Somewhat like the one's shown in the images: 

Answer 2

Europeans wore different dresses which were odd, unusual and bizarre before the 18th century.
________________________
Women usually wore long fur frocks with long sleeves and corsets.
Men wore well cut suits with long pants.

I have attached two pics, one of corsets which was abandoned and other was about their dress code. Hope dis helps you