Avidemux feels like it's a bit that.
Since ffmpeg internals are quite raw and not written to be accessed through a GUI, any video editor based on it would probably be quite clunky and weird and hard to maintain.
Maybe an editor that use modules that just build some kind of preview with an command explainer, or some pipeline viewer.
ffmpeg is quite powerful, but it's a bit stuck because it only works with a command line, which is fine, but I guess it somehow prevents it from being used by some people.
I've already written a python script to take a random amount of clips, and build a mosaic with the xstack filter. It was not easy.