Linux

Yeah, Kdenlive. You can do a job with it, but like most software, you need to put some time in to learn the ropes. YouTube is great for tutorials. I've used it to cut up screen recordings (recorded with OBS) and turn them in explainers, dropping in stills as title backdrops, even doing shrunken down videos that looked like they were playing on a laptop.
I was pretty happy with that anyway.
You can record voice overs directly into Kdenlive, but the audio editing is next to non-existent, so you're probably better off editing it in Audacity or Ardour and cleaning it up there, and then dropping it into Kdenlive.

For context, I'm a developer, not a graphic designer or anything, so me achieving any video editing results is a thumbs up :)