The Gimp is way too powerful to replace DPaint. And from the other end it is way less powerful as well if it comes to animation. That is, I could manage creating animations on DPaint in a few clicks, in The Gimp I wouldn't even know where to start.
However.... There is this little Windows program that actually does work like good old DPaint. It even uses the same short-keys. It is called
Pro-Motion. You can try it for free and have to buy it over time.