No I am not!
OM MY GOD! I AM!
is 'ty to człowiek' wrong?
yes. we don't use "to" sentences with pronouns, and especially not with ja/ty/my/wy. Although you would be understood.
The way you are saying this would be dirrectly translated to "You a human" You have to use the Polish word "Jesteś" which means, You are.
I also advice you dont compare languages as even though they are similiar they have many differences.
Why is it "iem" ending i czlowiekiem and not "em" ending?
Phonetics, I guess. -kem or -gem don't really exist in Polish, they have to be softhened.
Why not just człowiek????
Why is "jesz" not acceptable? I thought "jesteś" and "jesz" can be interchangeable.
No, "you are" and "you eat" are not interchangeable.
Jesz człowiekiem is grammatically correct, but it means that someone is eating while using a human as a fork or spoon.