Eli5: What determines if a nationality ends with -ese (chinese, japanese…), -an (Ghanian, Egyptian, American) or just the county itself (Thai)?

Question

Eli5: What determines if a nationality ends with -ese (chinese, japanese…), -an (Ghanian, Egyptian, American) or just the county itself (Thai)?

In: 4879

Answer 1

I always assume it depended on the last letter of the original word .
Hawaiian and thai is interesting difference. Most do end in -an though it seems the older the european country the different it is. British, french, belgium, swiss, ect.

Curious how latin and ancient greek did it. Hebrew as i recall put -im plural on end of country name for the people