Looking for application to do very simple 2D animation

I spend a lot of time creating system diagrams for presentations. I always use Inkscape to draw these diagrams. However I ran into a scenario where I wanted to animate them. The animations I'm looking for are dead simple. I want to be able to fade in, fade out, and slide basic shapes. The way I worked around it this time was by using PowerPoint. However, is there an FOSS alternative I could use? I would probably need to also export the animation into a gif or some other platform agnostic format. Bonus points for something that can use the images I draw in Inkscape.