Simple, todays alaska "native" have no dna from the other groups of "natives" who lived here before they migrated here. ADN had an article on it but I have other things to do.
You asked the question if there were others before todays natives and if so they would not be natives. It is a fact that there were others living here ( maybe the Clovis) before todays "native" migrated here. Todays natives are not native to Alaska. There are no different then anyone born here in Alaska. They have just been here a little longer. It is a fact that they are not the "first people". They are not related to the real "first people". But if they want to call themselves the first people have at er. You can call a Chevy a Ford but its still a Chevy.
"a person born in a specified place or associated with a place by birth, whether subsequently resident there or not." from the dictionary.
"a native of Alaska" One born in Alaska.