That's right. In Nehrim enemys do not levelup or get spawned according to your current level. which is a great improvement, in my opinion. always hated daedric armor-wearing bandits with ebony swords standing beside an old tent.
nehrim is splitted in different regions with different enemys and beasts instead. if you want to, of course you can visit nearly every part of nehrim right in the beginning, but it may not be the best of ideas for you would' t get very far.
Roland