The energy of the sun of course :3
Decomposers are important in the food web since these break down chemical substances.
The immune system, and the excretory system
(Honestly, all of them work to keep us 'healthy', but I believe these are the ones you're looking for)
Producers:
Hippos,elephants,cattle,antelope,horses
Primary consumers:
Seaweed,phytoplankton,algae,plants,Cyanobacteria
Predators:
Wolf,puma,lion,cheetah,lepard
