motorshield.h not detected even after downloading all the relevant libraries

adafruit motor shield library
adafruit motor shield v2 library

Why would you install both of these? The motor driver shield you have is either V1, and you need the first one, or it is V2, and you need the second one.

motorshield-master

Once again, why?

Do you really not know what hardware you have? It only makes sense to install ONE library that is compatible with that hardware. And, it ONLY makes sense to try to use code that is compatible with that library and that hardware.

A shotgun approach to installing libraries is doomed to failure.