When I remove your setting of character linear velocity, the sphere pushes the character when hit, a little bit. Maybe something is wrong with your code that modifies velocity. Note that there are built-in functions for setting both angular and linear velocity damping. Here’s an organized summary of physics properties.
When I set friction of sphere, ground, and character to 0.1, the character should move a lot more when hit, but doesn’t. Not sure why.
Edit: playing a little more it looks like setMassProperties() is resetting the mass you tried to set initially when creating the physicsAggregate. You might consider using physicsShape and physicsBody directly instead of physicsAggregate (which is a conveninece function designed for easy porting from physics V1).