IIRC
Clerics and the Acolyte background in 5e still need to a God in FR, and Divine Soul Sorcerers need to pick one as an ancestor/cause although no need to worship the same God your related to, and Druids get their magic from the First Circle (Nature Gods), no matter who or what they worship in 5e. Also the Zealot Barbarian doesn't make much sense without a Patron God.
The DMG also has a Piety system Larian could use if they wanted.
All the Gods and Warlock Patrons in-game have voice barks and Dialog (using the tag system), possibly more effects.
there are societies in the Forgotten realms, like Kara-Tur) that have ancestor worship instead of gods, or they worship the God-emperor.
Similarly, societies with totem spirits (Maztica) probably don't have a specific outer plane for their faithful, but you become one with the Bear spirit, or go on to hunt with the Jaguar god for eternity. You have some flexibility in the matter.
Does anyone know what/who the patron god of humanity is? Dwarves have Moradin, Elves have Corellon, Gnomes have Garl Glittergold, Halfling have Yondalla, even the Drow are stuck with Lolth. Does any god have a 'claim' on humans or are they up for grabs for anyone?
I think the lore of D&D is obscure(and sometimes it contradicts itself) but unlike other races, the humans do not have a unified myth of creation and they seem to have come from other worlds or they appeared in Abeir-Toril from several places at several times(It´s canon that The Mulan were first brought to Toril through twin gates to another world created by wizard rulers of the Imaskar Empire), and they exist in many worlds at once; so I do not think there´s a god that claimed humanity as his own that I know of; as @kanisatha said.
