So why are there so many
French words in English!

This is highly simplified, but......it's because the last successful invasion of England was undertaken by the French.

In 1066, William the Bastard (also known as William the Conqueror), invaded England in pursuance of his claim to the English crown. The invasion succeeded, and William was crowned William I of England, overthrowing the preceding line of English (Saxon and Viking) monarchs, placing French noblemen in positions of authority and wealth throughout England.
French became the language of the ruling class, English being pretty thoroughly repressed. Words changed depending on the status of the person: cow became beef on a plate, deer became venison, etc.
See this entertaining and informative quick video from RobWords.