Many words, such as "you", were not used in Shakespeare's time. Instead, people said "thou" and "ye". They said "bootless boil-brained clack-dish" as an insult, instead of "mindless idiot" or something like that. The people back then used this language every day. A common conversation would be ":Prithee get me a drink, laddy." "No, I'm too busy with my chores." "Nephew, get me a drink, and hold your tongue."
They did not use words like "primitive". They also did not use many phrases we use today, such as "workaholic".Many words we use today, such as "opera" were used in shakepearean times, but not very often, so they were not considered Shakespearean words.
Some other Shakespearean words are "tickle-brain", a kind of strong alcoholic drink and - well, we won't go into them. Did you know that "nephew" meant any younger male relative? Like, another common conversation would be"Nephew, ye wish for a drink?". A reason Shakespearean language was so different is that they lived in England and English English is different than American English.
The reason language was so different in Shakespearean times? All we know is that language changes, using different styles of speaking over the ages . Shakespeare's language sure changed!