Somewhat adapting the UQ style guide for simplicity and to minimise seductive details:
Generally, knocking something up in Keynote is quick and easy to then export and update. Some clean, minimal animations include 'Fade and move' (adjusting down the 'travel'; below), pop, line-draw, spin, and dissolve. I occasionally use heavy ones like Anvil, Crumble, or Trace when appropriate (e.g., when something 'hits' I use Anvil; when it's falling apart, Crumble).
Use animations so voice-over is timed to the visuals
Use meaningful pictures and/or a few key words to ensure those watching aren't totally reliant on the voiceover
The noun project is excellent for images that avoid being seductive (it’s cheap and valuable, but ask Mike if you want to try it)
Storyblocks is good for b-roll, but be careful to avoid seductive details (more expensive, so ask Mike if you want to know how to get it)
If displaying something complex, use call-outs, blurs, or highlights to show learners too