Cs, believing in Moshe means believing that the Torah he gave us is 100% true and dvar Hashem, and that his nevuah is above all other neviim.
What it does NOT mean, is that there’s something independently powerful or holy about Moshe without Hashem; see meshech chochma on the chait haegel; the mistake was that they put an independent emphasis on Moshe rabbeinu, and thought that without him there can be no other leader or way of reaching Hashem.
Tanach is full of pesukim which pine for the days when knowledge of Hashem – not tzadikim – will fill the earth,and we daven for it all day on rosh Hashanah. Nowhere in the machzor do we daven that the world know about rebbe akiva or the rishonim, achronim; they are important to get close to Hashem, as the mitzvah of uvo sidbak – clinging to Hashem, but that’s for jews and it’s a next step after basic emunah.
Emunah doesn’t start with moshe, it starts with Hashem; and that’s exactly the order in the pasuk. They believed in Hashem and in Moshe.
But when the jews sinned, the neviim didn’t chastise them for forgetting Moshe – that’s a big problem, but the bigger issue was forgetting Hashem.
When talking about goyim, it’s fine if they never even heard of Moshe rabbeinu; do you think west africans need to know tanach to be good people? The 7 mitzvos are logical; they’re supposed to gigure them out on their own. And according to most, if a goy sets out to believe in Hashem abd keep the 7 mitzvos as he understands them to be the reflection of Hashem’s will he will have olam haba. He has solved the riddle of the universe, he is a person worthy of praise.
The goal in teaching emunas chachamim is that they guide us and we trust them that they are guided by ruach hakodesh and hashgocha. When we lose them, we lose that ability to access Hashem’s Torah on that level and hear their guidance. But does that mean i will want every goy in the world to hear the name rav moshe feinstein or rav aharon kotler? Why do i care if they know them, as long as they know there’s a creator and maintainer of the world? Even the name of Hashem, as important as that is for Jews and how powerful that is – we rejoice when arab non jews acknowledge Hashem in their own language, because that’s the most important thing.