Cholesterol, what is its deal?

when i decided to stop eating meats and limit dairy, (call me stupid) but i eventually learned cholesterol is in 2 sources
1)people
2)animals
Okay
so, then it was clear if my food has no animal products then it has no cholesterol and vice versa

now, on the news they are still bringing up Trans Fat (so 5mins ago,lol)
they said, it increases bad cholesterol
and decreases "good cholesterol"
Good??

what’s up with that

bonus question
what exactly is protein?