hi i am a lvl 21 human and well i am now spending most of my time searching for dbs how ever every mob i kill that has a db does not drop can some one help me

It's all luck based. Roughly 95% of DBO is luck based. Keep killing these DB mobs and eventually you'll get a drop.

i know about that but at other forums they say the mob have to be at least in 5 level of yours

Yeah! There is no problem in going higher though, even though it will be hard. I only go two levels below mine when hunting. If you are level 21 there are level 20 super dinosaurs you can farm at. They give more chance due to being supers

where are the super dinos in the wirlpool hill

I suppose so. Where the dragon skeleton winds up the rock.