I recommend you use composition versuses inheritance.
Basically, create a sprite node and give it a kinematic2d child or just have a node and have it have a sprite and kinematic2d as children. By doing this you can have both thing in a single node without needing to inherit two scripts.
Code speaks through signals or direct calls
Sprite -> Sprite Script
-> Kinematic2d -> Current Script
Node2D -> Connecting Kinematic and Sprite or Other Stuff