Answer:
What stays the same size no matter how much they weight?
Where humans breath liquid?
What relies on columns but isn't a house, and asks for help but can't speak itself?
What force and strength cannot get through. I, with a gentle touch, can do. Many in the street would stand. Were I not a friend at hand.
What can be swallowed, but can swallow you?
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?