When you don't draw your favored card type in your opening hand, are you required to draw anew until you get the card type, or is it optional?
Required.
Draw Starting Hands. Each character card includes a hand size for that character. Draw that number of cards from your character deck. The character card also lists a favored card type; if more than one is listed, choose 1 type before drawing. If you didn’t draw at least 1 card of that type, discard that hand and draw again, repeating as needed until your hand contains at least 1 card of the specified type.
Nothing in there indicates it is optional. Just like you have to draw the number of cards indicated in your hand size, one of those cards has to be your favored card type.
This can be a bummer if you're playing Seelah (favored card type: armor).