Shot attempt or not

[Jake80]

Had this situation last night and not sure if I got it right. A1 receives a pass at the free throw line. As he is about to attempt the shot, B1 jumps to contest the shot. Ball is released by A1 (couldn't really tell if voluntary or it slipped). Ball goes up in air a couple of feet and is not touched by B1. A1 takes a step and recovers the ball in the air. I called a travel, now I'm not so sure. What do others think constitutes a legimate try for goal? Do you look at things like the distance the ball travels or just try to interpret the player's intentions.