I’m a HUGE (not size wise, I mean I play it a lot)baseball player, so I may be able to help. I also coach kids who have no idea what so ever how to throw.
First to get more power USE YOUR LEGS! Almost none of the power is generated in the arm its just an extension of the rest of your body (longer an object is the faster it spins!)
Next use rotation in your body to generate more speed, notice when any pitcher or QB throws a ball at first they have shoulders pointing at the target, so your chest is perpendicular to it.
And have a long follow through in your motion, you don’t want to be slowing down your motion before you let go of the ball!
Finally do not stay upright the whole time at the start of the motion you should be leaning back slightly, and when you finish you should be way forward. Look at this video, at about 4 seconds in his body is at a “T”. The bottom of the “T” is his left leg, the back of the “T” is his right leg, and the front is his torso, and arm. Now I’m not saying pitch the basketball, I am saying try to use some of the mechanics that are used in pitching and incorporate them into the basketball throw.
Mechanics are the only quick way to improve distance.
One last piece of advice is USE LEGS I cant emphasize that enough! So many people don’t use legs enough, even people playing for years!
Hope I helped!
Feel free to PM me and I can go in much more detail.