https://inkscape.org Vector Images

https://gimp.org Images

https://krita.org/ Images

https://obsproject.com/ Record your desktop

https://kdenlive.org Make videos/audio compilations

https://blender.org make 3d things

https://unrealengine.com make movies/games

https://openoffice.org make documents and presentations

all free, but not all OS'es supported (though ever one is supported in windows)

You could literally spend a lifetime working and learning these.

There's also for programming:

https://www.eclipse.org/ - Java

https://visualstudio.microsoft.com/ - C++, C#, bunch of others

https://inkscape.org Vector Images

https://gimp.org Images

https://krita.org/ Images

https://obsproject.com/ Record your desktop

https://kdenlive.org Make videos/audio compilations

https://blender.org make 3d things

https://unrealengine.com make movies/games

https://openoffice.org make documents and presentations

all free, but not all OS'es supported (though ever one is supported in windows)