ELI5 Energy Drinks - what’s in them beyond caffeine?

What in energy drinks provides stimulus over and above that from caffeine? Are they superior to coffee or tea? How did Pepsi and Coca Cola start out as energy drinks? Why are their health warning labels on some energy drinks? What are the benefits of energy drinks?
... we explain like I'm five
Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: svijetokonas, gingrpenquin, seaztheday, harrietbeadle, astroember, -kibbles-n-tits- and m_t_rv_s__n
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