Answer:
I am a busy worker who is a water mammal.
I fly when I'm born. I lie when I'm alive. I run when I'm dead. What am I?
I am rarely touched but often held. If you are smart you'll use me well. What am I?
I describe a toilet cleaner as well as one of Santa's reindeer
I go up but never come down. What am I?
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.