Weapon proficiencies are an important part of D&D character race and class, they help to create a cohesive narrative around the character and breath life into their essence.
For example, the Elves naturally have proficiency in arechery due to their sharp eye and steady hand, they can be great at range. Halflings are great rogues due to their small size are naturally proficient with daggers and shortswords... etc...
I do worry that many players of BG3 may miss much of the nuance around the D&D 5e law regardless of understanding the basic rules.
Okay, but, aside from Dwarves getting an assortment of axes and hammers, and elves getting a couple of sword/bow/crossbow proficiencies based on sub-type, that's not really a thing in 5e. Halflings do not, for example, get any kind if innate weapon proficiency. Outside of that, you get your proficiencies from class, and so if you're a cleric, as you suggested, then you have at least all simple weapons to choose from...
So, I'm still really not seeing anything at all that would even remotely suggest that:
It is possible to create a melee Cleric at higher levels [...] though you are limited to bludgeoning weapons such as maces, etc.
That's feel like you're pulling it out of a personal conception/stricture that really has no grounding in anything (except possibly some rules in older editions that have rightfully been discarded by now), as far as I can tell.
You can favour whatever weapon you like (usually one favoured by your deity, if you're a cleric), within the simple weapons group, as well as any weapons you happen to get from your race or background... there's nothing at all restricting you to bludgeoning damage choices.
