Current AI image generation models work in a 2D space, and they function by associating words with patterns they find in the image data they're trained on. Hands, forming complex, flexible 3D shapes, can change in appearance greatly depending on how they're posed and what angle they're viewed at, and a lot of them found in the training data are just tagged as "hand". Thus, when you generate an image of a hand, it's not aware it needs to create one posed in a specific way and goes with a weird mishmash of angles. I've heard using keywords like "reaching" to reduce ambiguity can help, but I haven't tested it myself.

As for faces, the major models should be able to handle faces, so you might have them misconfigured. Craiyon just isn't very good.