This is a preference thing: there is no right or wrong answer here. You are not required to bring anything aside from your ID and insurance card if you have them. The rest of your bag should be things that bring you comfort. 

If you do a labor and& delivery tour at some point before you deliver (most hospitals offer this), you can ask what amenities they have that you may want (bath, bouncy bouncing balls, fan, etc.) If they do not have these things then you may want to bring them. 

Things the hospital will provide: sanitary pads for you after delivery, diapers, formula, bottle nipples, food/drink, gowns, and hygiene products for showering.

Things you may want: phone charger, socks, snacks, your own clothes/robe/toiletries that you prefer, multiple changes of clothes (you may be very sweaty/uncomfortable during the labor period), slippers, shower shoes (hospital showers should be clean but still), etc. Think about going away on a trip to a hotel for 3 days or so and pack whatever you would take for that