why is shakespeare knownn as father of english drama

Shakespeare is called the father of English drama because the template provided by his plays became the one that seeped into all subsequent forms more than anything before it. Whereas he would have been imitating the form of the Roman dramatists (5 acts, the way he uses certain characters), his appropriation of these forms provided a vocabulary for later dramatistis. Examples would be the use of the soliloquy, the distinction between status of characters (low/high class), and the use of revelations throughout the play. Again, he didn't necessarily INVENT these things but by appropriating them all into one place, provided a template that makes him the "father" of what English drama became.