Umm, theres like ten thousand different weapons in this game.
No, there is only a handful of weapons and the rest of are just mods for the weapons. Of which the player gravitates to certain mods for a given weapon based on their play style.
If going the sneak route, players tend to go with rifles or pistols. Rifles you end up with a hunting rifle with the 50 cal receiver on it as there isn't a native 50 cal receiver based gun in the game. With pistols usually the 10mm pistol is the best as the 44 doesn't allow for a suppressor despite the superior damage. With the exception of the Deliver which is a very nice unique pistol that is 10mm based that allows for a suppressor and looks like a walther ppk. But then that gun doesn't allow scopes so sniping with it is a bit more problematic. But basically here is the break down for pistols
10mm
10mm Deliverer (truly unique pistol in the game)
.44 revolver
Flare gun (not really useful for combat)
Gamma gun
Alien pistol
Everything else is just mods or legendary prefixes. Yes even the "unique" pistols like Kellogg's pistol is technically just a legendary mod prefix. The same thing goes for rifles. At least with most rifles you can mod for ammo type to a degree and whether you want non-automatic or automatic (but not for every ammo type).
Assault Rifle
Combat Rifle
Hunting Rifle
Submachine gun
Railway rifle
Syringer
Gauss rifle
Those are the pure rifles types. Everything is just mods and legendary prefixes on top of that.
There are the gun types then that go either way based upon the stock mod. They are either pistol or rifle.
Pipe guns (.38 based)
Pipe Revolvers (.45 based)
Laser guns (although there are 2 different looking model with plain grey and institute white with institute being slightly less damage for higher rates of fire based)
Laser Musket
Plasma guns
Shotguns is even less diverse as there is only 2. So if your main choice is to be a shotgun based player in the game, your gun diversity is ridiculous low to choose from. Of which you can choose:
Combat shotgun
Double Barrel shotgun
Heavy weapons is a bit more diverse surprisingly, but not by much. Here is the base list of heavy weapons:
Fatman
Missile Launcher
Minigun
Flamer
Broadsider
Junk jet
Cryolator
That's it for all the guns. There is even less to choose from when it comes to melee. Which melee falls into 3 categories really. Fast speed, medium speed, and slow speed. With more damage per hit usually the slower the melee weapon. Or bladed, blunt, and fist types can be your melee categories if you prefer to arrange them that way.
There isn't thousands of guns, but merely a few dozen platform types with several mods per platform. The problem is, that the mods are done that each mod type up is better than the previous usually. Which means there is one top end configuration for each gun platform your character wants to use and that is it.
Even then, many of the guns aren't really worth using due to lack of ammo for them in the game. Alien Blaster, and most of the Heavy guns, especially the Cryolator and Broadside, are pretty much worthless to use. There is a set finite small amount of ammo for them in the game and that is it. Other guns also make little sense like the .45 round guns. Of which only pipe revolvers, combat rifle, and the Submachine gun use. The damage from those platforms if very low when compared to the output from others similar style guns.
So when I say the game suffers from a lack of weapon diversity, it most certainly does. I also don't consider mines and grenades as main weapon choices for a character as they are supplemental.