iMovie is described as 'With iMovie for iOS and macOS, you can enjoy your videos like never before. It’s easy to browse your clips and create Hollywood-style trailers and stunning 4K-resolution movies. You can even start editing on iPhone or iPad, then finish on your Mac' and is a very popular Video Editor in the video & movies category. There are more than 100 alternatives to iMovie for a variety of platforms, including Windows, iPhone, Mac, Android and Web-based apps. The best iMovie alternative is Kdenlive, which is both free and Open Source. Other great apps like iMovie are OpenShot, Shotcut, DaVinci Resolve and Avidemux.
Kapwing has an excellent video maker that lets you easily import photos, videos, and GIFs then merge them together into one continuous video. It's free to use (with no trial period), and you don't have to download any software.