I'm considering the first IFT "Not Successful", in that it didn't insert Starship into a near-orbital trajectory. Even though personally I think it was a successful data gathering flight. The guiding principle for success is something like "Did this flight prove to customers their payload will go where they want it to go?".

Essentially, will SpaceX make 500 launches that a customer would consider proves satisfactory reliability and safety of the system by Jan 1st 2030.

A "successful launch" means any launch in which:

In all cases it doesn't matter whether the booster survives.