I don’t know if there’s any easy app to create animated loops. Maybe it’s possible to use some sort of video game software and insert your own sprites.

I started with a hand-drawn sketch of elements I wanted to include. Then I used adobe illustrator to draw all the elements. And put everything together and into motion with after effects.

I know there are free / cheap alternatives to illustrator, but not quite sure about alternatives to after effects, which is why I stick to it.

That being said, my background is in illustration and graphic design, so the jump into animation is shorter than for someone starting from scratch.

However, there’s a lot of methods to create animation. Even low tech. I recently saw these beautiful paper-doll animations that was done with sticks by hand, I’ll link it if I can find it.

Sorry for not giving a short and easy option for your question.