Who’s Jimmy Fallon?
His best work is some Capital One commercials with a baby who throws cereal at him.
He's an entertainer.
The purpose of an entertainer is to provide us with entertainment. To amuse us and to temporarily divert us from reality by way of providing us with a "performance" of some type, be it singing, dancing, acting or just generally making us laugh by being goofy.
Back days of old, kings and other monarchs would keep some entertainers on hand in their court for both their own amusement and for that of their subjects. So while something serious was going on that day, like a be-heading or a torture (quite common back then), these entertainers would relieve the tension by capering and prancing around with their silly antics. They called them court jesters.
“Who’s Jimmy Fallon?”
Who’s Barack Obama?