Web - free.
Bitable makes it easy to create short animated videos using a wide variety of templates to which you can add text, music, and images. The free version includes a Biteable watermark on all videos you make.
Mac - pre-installed.
Using iMovie, you can create and edit videos on a Mac. You can choose from different effects and transition options, as well as add music and text.
Web - free.
WeVideo allows you to create and edit videos, with easy to use tools and many effects to choose from. The free account option limits you to 5 minutes of published video time, and adds a WeVideo watermark to your videos.
Web - free (you log in with your Google account).
YouTube Video Editor allows you to do basic video editing of videos you have uploaded to YouTube. There is a library of Creative Commons videos to practice with.