Some options: Einstein, Da Vinci, Mao, Elvis, Hitler, Stalin, Walt Disney, Princess Diana, Shakespeare, Gandhi, Bill Gates, Madonna, Piccaso, Pamela Anderson.
Outside of the religious figures, I think Mao Zedong could be a reasonable chance with possibly Gandhi behind him.
60% of the world's population is in Asia and almost a third of that is in China. All generations in China would be aware of Mao, though many (especially rural) would have limited awareness of western icons or even key religious figures.
Obviously India is very populous also, but outside of Gandhi and some Bollywood stars, I'm not sure if there would be a common personality that all castes and generations would know.
Africa might be too sparse and disconnected to really hold much sway and Europe accounts for only about 10% of the world's population.
Including religious icons, Buddha would probably not make the top two and while Hinduism has a significant following, its identities vary. You'd comfortably pick Jesus and Mohammed as the top two identities.
I think I'd rank it:
Jesus
Mohammed
Mao
Gandhi