Number of natives in a raid is not tied to your level. It's tied to the number of tamed NPCs you have, including unique characters.
And the level of the raid is tied to the location.
Player's level has absolutely nothing to do with raids. Even if it does, it's so negligible, you'll need to cheat yourself million levels to notice it.
I am level 71, and the raids I get are level1 - because I never left the starting beach, and the number of natives is 12 - because I have around 20 friendly NPCs in my base.