My first recommendation is to use a higher FPS. It’s advisable to use a higher FPS as it makes it easier to obtain a smoother look on your animation.

Here’s an example of a animation at 10 fps

Here’s the same animation at 15 fps

Also, as the stickfigure jumps, you should try to move his limbs more than just turning the main node to the side.

One more thing you can try doing (though don’t grow reliant on it) is tweeting, which will help make your animation smoother by adding in between frames. However, it can be glitchy when turning stickfigures and such, so you will need to learn how to use it efficiently if you plan on using tween a lot.