OpenMW is a free, open source, and modern engine which re-implements and extends the 2002 NetImmerse engine for the open-world role-playing game The Elder Scrolls III: Morrowind. Like the Construction Set for the original Morrowind engine, OpenMW comes with its own editor, called OpenMW-CS, which allows the user to edit or create their own mods or original games. Both OpenMW and OpenMW-CS are written from scratch, and aren’t made to support any third party programs that have been added to the original Morrowind engine to improve its functionality.

OpenMW is not a “mod” to Morrowind. It is an entirely different game engine that does not use the original executable file in any way.

Yeah, basically if you want to play Morrowind, at this point you want to do so by using OpenMW. You do need to own the original game, but OpenMW makes it much easier to run on modern operating systems and has lots of quality-of-life improvements, like higher resolution, higher viewing distance, as well as most loading times eliminated.

Because this thread is being helpful, and I didn't know....

OpenMW has an FAQ and here is a link to "Do I need Morrowind?" https://openmw.org/faq/#do_i_need_morrowind
The answer is "Yes", but the link has more details.