Bare in mind that the Bird compilation is from his entire carreer while Curry's is from one season at the age of 30.

Bird has at least 5 feet of room on every shot as he begins his shooting motion. Every shot is with time to get his feet set. Nothing is off the dribble or in the process of shaking a defender. Steph probably shoots greater than 60 percent on shots like those.

Steph shoots 47 percent on catch and shoot three pointers for his carrer and that is on massive volume--usually with opponents draped all over him and often from 30 feet.

Steph takes shots off the dribble with multiple defenders all over him. He shoots from way behind the arc. These are things Bird never even attempted. Bird never created his own three point shot off the dribble, so to say he could is just not supported by any evidence anywhere. So yeah, we will never know--and that is being kind to bird.

Literally no one who seriously follows the NBA or makes a living in the NBA believes Bird is a better shooter than Curry.

https://www.youtube.com/watch?v=Eee2TkiclIM
https://www.youtube.com/watch?v=tk51i4zjeqQ