Why did Leeloo jump off the the Science building only to land in the cab? Was she attempting suicide to protect her knowledge, or was she taking some kind of temporal chance based on something only she could see?
There is no indication in the movie beyond the brief time she closed her eyes immediately before she jumped which could have been her praying, having a vision of when to jump or just steeling herself for a "this is gonna freaking hurt" however nothing else in the movie points to her having any type of physic ability
It is probable that she thought she could survive and it was either jump or be captured.
Leeloo is not human it is highly doubtful a normal human would have survived the initial impact with the cab especially considering she broke through the metal instead of pancaking it (admittedly that could have been due to the anti grav system of the cab rather than actual speed and we dont know what kind of metal it is)
The girl feels trapped. She looks down into the endless 450 below and all the cars flying underneath her. Then she raises her arms... and dives off.
57 INT. POLICE CAR - NIGHT
COP (in the car.): Christ! She dove off!
For the record, the novelisation of the film is no help.
The girl seemed only too happy to comply.
She smiled and raised her arms. She stood on her tiptoes, looked down 450 stories, and—
“Christ!” said both cops at once. “She dove off!”