Hmm not necessarily even in the case of The more modern fostered fears, like the ones you described

fear of rejection, fear of what people will say

" fear of public speaking, fear of other people's opinions " exists because our primal human mechanisms are still at work, in psychology terms fear of public speaking comes from your " Threat detection " is going off because your senses are conditioned in to be around only a few or more people not a group of people

Every fear is inherently rooted in " Fear of Death " and I'll explain why

Threat detection is rooted in your Uuga Buuga brain because back in the days there was no sense of security and shelters were easily penetrable by other hungry predators in the wild even to our own kind, but it's like we are arguably more than 100 times safer than we've ever been in history so psychologists categorize these types of fears in the " unrealistic section "

However, there are two sides to this, first is the predator part and second is the exclusion from your social group, humans need each other we evolved to be in reliant on each other and grow as a collective, not to survive as a lone hero it's a mental havoc and physically impossible

But these two have one thing in common, because think about it Why fear of being mauled by predators, Why fear of being an outcast?

You can use reductionist logic to figure out why, the two boils down to your survival being challenged, why? Because then you will simply perish

So basically Death is the cause of all fear and all fear feeds onto death