Answer:
Never ahead, ever behind, yet flying swiftly past; for a child, I last forever; for an adult, I'm gone too fast. What am I?
What loses its head in the morning but gets it back at night?
I have been the beginning of ideas for all time yet I am just one simple small object the things that you can use me for can be frustrating and also I can be pretty. I have some of the most valuable thing in the world on me yet almost everyone owns me.
You use a knife to slice my head but you weep beside me when I am dead
I can be simple or I can be complex. I can be found in this riddle or in everyday life. I can be shapes or even colors.
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.