My wife (a music teacher) was a Mac only video editing person. She now uses Open Shot almost exclusively, even though for $40 I bought her Sony Vega (she was complaining about Open Shot at the time). I think Open Shot is a good gateway to Blender or other video editing tools. She does all her stay at home videos on Open Shot now because she can do it so quickly. I would say it took about a week to get really comfortable making simple videos.

Not OP, but I think OpenShot is made exactly for this kind of simpler editing. It's akin to Windows Movie Maker.

ffmpeg - you can do declarative editing combined with a Makefile. Clips can be previewed with `mpv --osd-fracitons` or equivalent.