Even if the sign for ball was the same the world over most sign languages don’t communicate with individual words that form a sentence, as in speech. There could be a different sign for bouncing a ball, throwing a ball, catching, kicking… A very long spoken sentence may be signed using few signs combined with facial expressions.
What may be a correct sign in BSL could be a rude, insulting gesture in Japan regardless of whether it is recognised as sign language or not.
As far as I know all forms of sign language has signs to represent the alphabet so uncommon words and names can be spelt. There are at least 5 different alphabets so it makes a universal sign language difficult.
Just as the spoken language has developed over many years, so has sign languages so naturally they are different.