Everyone's answer are great.
One thing I would add is:
C and C++ - you dont have a string class. you have to manage pointers. ITS SUCH A PAIN - however on the flip side - you can learn a lot about class constructions this way too. Some may argue that it is not needed however root basis languages are very helpful (also considering it is core to Linux boxes).
Another similar trend would be why learn jquery when angular and vue does everything for you. A) that is not true b) you will always be able to appreciate and refactor code that spawn from the root programming into the more modern one.
At the University of Concordia during my 4 year stay I saw them flip from C to C++ to Java in terms of intro to OOP. C was harsh - C++ was rough and Java after a while you appreciate it only because you went through C and C++.
If you are asking this question due to a time factor, my answer is still the same: you will know more about how internally other languages work if you know the the parents of the language (ever wonder why memory management is important ... its about them pointers and other things)