Kaepernick wore this Fidel Castro shirt and Malcolm X when talking to the press in 2016. The whole kneeling thing is his expression of Marx's class warfare. Marxism is what underlies Fidel, Malcolm X, black liberation activists like Kaepernick and BLM, and liberals complaining about whites and capitalism. They seek to divide people to create social upheaval, which they believe will lead them to taking power.