Depending on the clothing and/or shoes, a snake may not be able to bite you. It would also depend on the species, as I wouldn't be afraid of a garter snake. Against a lion or gorilla, you stand no chance especially if it is male silver back gorilla or a male lion.
Personally, i think the lion wont as likely kill you as food that likely. They are actually quite lazy (in the day). They dont attack the tour cars or any of that on the savanna. Gorillas are more likely to see you as a threat i would think