The idiom "things are right and people are not the same" comes from Wulingchun written by Li Qingzhao in the Song Dynasty.
It means that things are still the same as before, but people are no longer the same people. This idiom is generally used to express how things have changed and to remember old friends.
The antonym of things changing and people changing is immutable.
The synonym of "things are the same and people are not" is that time has passed and circumstances have changed, people are not the same as things, things have changed as time has passed.
This idiom has been widely used in modern times.