Answer:
I am not a toy though many use me for pleasure. I have a butt but I cannot poo.
I am used when you jump off a bridge for fun.
Why are there no living cats on Mars?
I never was but always will be. No one ever saw me but everyone knows I exist. I give people the motivation to better themselves every day. What am I?
I am black and white. I have strings I have keys. I make sound without my lips. I make dough with no flour
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.