why world war 1 started

A-H started threatening Serbia so Serbia was like "oh ya really? well awww ya i got Russia!" and Russia was made allies with Serbia. Then A-H thought "oh, i better get some friends then" so Germany joined A-H. then Great Britain joined Serbia and etc. After alliances were made everybody mobilized and FRANCE started making battle plans to attack Germany. So Germany was all like "oh i see how it is!" and they made battle plans to totally own France. And thats how it started. In my opinion.