Why do we have saliva in our mouths?

Many reasons: Saliva keeps your mouth moist, helps tongue function & starts the digestion process with an enzyme called amylase. Saliva antibodies & proteins are helpful in reducing dental bacteria & bacterial infections & also acts as a buffering agent which helps protect against the acid which would otherwise damage tooth enamel and lead to decay and tooth loss.

Several reasons: Lubrication and to initiate digestion.