So if god cares about humanity and our salvation, why do you suppose that he only revealed himself to some ancient middle eastern people? [Spirituality & Religion]

Why wouldn't he reveal himself to the different cultures and populations across the world? After all, this was a time when the world was much larger and the global dissemination of information was not only impractical but downright impossible.

So why don't we see diverse cultures all sharing a fundamental religion that could be recognized as christianity?

If god actually wanted to save all his humans, why do it in such an objectively ineffective way?