Not free but low cost: www.thebest3d.com has PD Howler. In fact there is also a free version based on v8.2 for home use, learning edition so to speak. Try and see if you like. If you like to draw with a tablet and create animations frame by frame it should be usable. There’s much mroe to it though. See the latest evrsion 9.5 and 9.6 features for example, with lots of greenscreen compositing focus and 3D landscape creation with erosion, sediments, clouds etc… for background and fly-through as well.
Perhaps a good way to assess what’s possible with Howler is this trailer based on v9.5:
That one is a bit more oriented towarsd game developers, content creation in such that is.
Oh, addendum: just a quick note, this goes back to v5, there is a Frame painter, for some types of animations this is very useful. From just a few (2-4) frames you can easily populate an animation of frames that lasts many seconds.
here on youtube:
The Cowboy shorts were done with the Framepainter, in part.
Here’s a more recent look with v9.5’ish :
https://www.youtube.com/watch?v=n2arHDjoWdY (My name is Mush)
The finished animation: https://www.youtube.com/watch?v=Wl3FWAGkxUU
the challenge was to create a 20-second animation from just one image.
That image can have a lot of details and by using parts of those and flipping them sideways you can create a few base images and then the Framepainter can further wiggle it to make it look alive.