Do I need to know Bourne's backstory before watching Jason Bourne?

No, you don't need to know any backstory.

The new Jason Bourne film tells a more or less standalone story. It's loosely linked to the previous films - in that Bourne is a former CIA assassin who's no longer involved with the agency, while certain high-up figures within the CIA still want him 'brought in' or killed - but all the necessary information is given to you early on in the new film, so you're not left wondering what's going on or who everybody is.

It's perfectly possible to watch and understand the new film without having watched any of the earlier films in the franchise. But if you're still worried about being able to follow all the characters and relationships, some of whom are introduced quite fast, the following cast list taken from Wikipedia (from which I've removed one spoiler and added one explanatory note) may help:

• Matt Damon as Jason Bourne, born David Webb, a former CIA assassin who disappeared after publicising details of the CIA's targeted assassination programs [including a program codenamed Blackbriar].
• Tommy Lee Jones as Robert Dewey, the current director of the CIA and leader of the Iron Hand program who holds an intention to take down Bourne after the exposure of Blackbriar.
• Alicia Vikander as Heather Lee, the head of the CIA Cyber Ops Division.
• Vincent Cassel as the Asset, a Blackbriar assassin working for the Iron Hand program. The Asset was captured and tortured as a result of Bourne's actions in The Bourne Ultimatum and harbours resentment toward him because of it.
• Julia Stiles as Nicolette "Nicky" Parsons, Bourne's former Treadstone contact in Paris whom he sent into hiding in The Bourne Ultimatum.
• Riz Ahmed as Aaron Kalloor, the CEO and founder of Deep Dream, a social media enterprise.
• Ato Essandoh as Craig Jeffers, a CIA agent and Dewey's right-hand man.
• Scott Shepherd as Edwin Russell, the Director of National Intelligence.
• Bill Camp as Malcolm Smith, a former CIA analyst who retired to the private sector.
• Vinzenz Kiefer as Christian Dassault, a hacker, whistleblower, and the leader of a group of privacy activists.
• Gregg Henry as Richard Webb, Jason Bourne's father.