I know Krita has a decent animation tool, but it's only raster, and I haven't encountered a really good vector tool yet.
The biggest downside to Blender is that the UI can be a bit intimidating since it covers so many aspects of CGI.
It's by far the most powerful and versatile piece of OSS I've ever used. I'd heavily recommend getting into it if you're a creative in general. It also has a really nice community to help out when you inevitably get lost in the menus.
I've been building out some backend stuff lately so there's a bunch of new features waiting to go in. https://github.com/Logicalshift/flo_draw has some demonstrations of the sort of procedural animation features I'm planning on adding, for instance.
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This code was open-sourced in August 2021 when Haiku shut down the commercial collaboration/storage services connected to Haiku Animator.
What limitations does https://www.synfig.org have?
Usecase: export to Discord / Telegram animated stickers and my Godot Engine extension module for lottie.
Right now, I have a couple-year-old permanent license to Toon Boom, which is very good, but of course it is very much not open source (and I do not believe they even let you do permanent licenses anymore). I'm not an animator, I just play with stuff occasionally, so I can't really justify ongoing costs, which is part of why I would prefer an OSS version.
And with respect to color management and Wayland with the rumored next release of nvidia drivers potentially supporting Wayland that's about the only thing that would stop me from switching on all my machines. I know there is an open issue for working on that in both the Wayland official protocols and wl-roots so hopefully soon.
As for After Effects / Premiere Pro I've been using DaVinci Resolve / HitFilm.
Of course Blender also provides everything you'd need for visual effects, tracking and separate passes since it's a full 3D suite as well.
Honestly, video editing can be crashy and resource-intensive so don't be afraid to pay for something.
However, even with such a simple project, none of the three FOSS tools were easy to use, and all were barriers to my efficiency and creativity. I then searched for commercial offerings, and have been using Davinci Resolve, where even the free basic version was light years beyond the FOSS choices in terms of speed, ease of use, and features. As someone who uses FOSS tools (GIMP, Inkscape) for ideological reasons, I was a bit disappointed by how large of a gap there was between FOSS and commercial video editors. I haven't looked at the FOSS versions since then, perhaps they have improved.
And only $300. Once. Resolve is amazing. It replaced both Premiere and AE in my studio. Not bad for something that used to cost about $600k. You can get away with a hell of a lot in the free version as well.
History of Resolve: https://www.youtube.com/watch?v=7WvP5_HFQSk
There are issues of course - memory leaks and odd GUI handling on Windows in particular - but I've had the same sort of issues with Adobe products as well.
A really awesome thing about Inkscape for me is how it uses standard SVG as its default file format. It makes a lot of sense and makes the raw artwork highly exportable and flexible.