Yep, a concept that MS-DOS inherited from UNIX, when they added directory support on MS-DOS 2.0.

However, even UNIX later adopted the folder designation for its GUI variations.

http://toastytech.com/guis/unixpcorganize.jpg

http://toastytech.com/guis/unixpcerrors.jpg

http://toastytech.com/guis/sv411fileview2.png

https://docs.oracle.com/cd/E19504-01/802-5817/6i9i42q3l/inde...

There are plenty of other examples of folder use, so it isn't something that Microsoft just decided to invent for Windows 95.