all the people还是all people

all the people 所有这些/那些人（特指某个范围内）
all people 所有人（泛指）

All the people in this park are having a good time.
All the people in this country speak Spanish.
You, of all people, should know what kind of person is.
All people want the same things in life, health, security and happiness.

都可以，all the people指的是特指，all people 指的是泛指
如:All the people in this park are having a good time.
All the people in this country speak Spanish.

You, of all people, should know what kind of person is.
All people want the same things in life, health, security and happiness.
自己把握一下……

都可以，all the people指的是特指，all people 指的是泛指

两个用法都存在，略有区别。