There are exceptions, like Eternals included in Marvel's Patheon Handbook while not really being descendents of Elder Gods but offshoot of humanity. (Also they have divinity much like Asgardians and Olympians, like they didn't get dropped in Chaos War.)
Skrull Pantheon also have an Eternal Skrull and a Deviant Skrull among them. There is a kinda vauge line here.
Second-Generation Gods/Demons are said to be the remaining energy of Elder Gods shaped and given form by the thought of men, Eternals also got mistaken as real Greek Gods.
Maybe divinity somehow do come from faith in some way. It varries with writers.