All games start with player spinning in circles looking up. With this issue the enhanced version is totally unplayable. The original quake 2 plays fine. Any help would be appreciated.

The only device I have connected is a keyboard and a mouse.

then I have no idea

(I didn't play Q2 Enhanced yet, there is gamepad on/off option as I heard not sure about additional options there)

Wireless maybe 6ou forgot to unplug/disable in OS?
Aware of additional tools come with devices. Any hardware devices. NV GeForce Experience are not the driver and shouldn't be installed at all. It only make game work worse. Nahimic app is not audio driver. And so same for input devices. Most tools they are come with is not driver related and junk apps make work device worse. Some came with hidden Overlay did not appear in games but make visual(!) glitches. Like LogiOptions.exe by Logitech. Even if they not - they not needed. Disable or better uninstall such tools. They can be a reason for such issue you have.

Some USB or Wireless devicemaybe incorrectly detected by OS as input device. From ingame settings probably turning off some directinput options help if there is such hacks (eg control input directly skipping OS settings options, direct acceleration option). Turn off gamepad support.
Issue is not in the game or not in first in the game. Issue can be from additional media buttons on KB and inbuilt controller for it + how OS recognise them. At least it is not the game if all ingame "direct access" options turned off.

Best and best for gaming - is simplest wired devices (eg just standard 3-buttons wired mouse). And no additional tools. No DPI buttons too... maybe (probably better install additional soft set some middle DPI frequency? and uninstall tool after that?).

If you sure anything unplugged/off maybe some input wrappers can help. Try to duckduckgo-it for them (maybe on PCGW). Although that looks like game fixers and maybe even partially caused by games - first they are DirectX/OS issue fixers. Because it is DirectX. There is no anything "game do/not support". Even all RTS support gamepads (if allow bind keys). Or any input devices. Games support only DX Dinput (or d3d for video output and else components) and how it's work depend mostly on which version game use or which device use. There is some standards features in differ versions like digital/joystick/digital+joystick(analog) devices support, move controllers support or nowadays version Xinput with own standards (eg controller hotplug, which one is optional depend on game for legacy Dinput games).

Any additional buttons from any devices by OS will tell the game it is Button #1-*. Media buttons on Keyboard too. They are media for OS but regular buttons for game. Wheel volume Controller on KB also is a two buttons even if they are not. Because they are actually.

And some old games got digital re-release updates with non-native wrapping method to support Xinput. So any device should be connect or unplugged before game launch still same as for old game Dinput version.
Not the case now it is New game release. For old games such issues can happen opposite if you unplug some USB device but after game launched.

I tell this for another reason. Default schemes is Xinput standard for MS gamepads only. If you have non-Xbox scheme gamepad, Sony gamepad (Xinput but with limitations) or legacy DInput or if it is old game - there is no default schemes for devices. Ingame input options should be first reset then manually rebind. And for this it's not just about DInput but XInput too so about Q2 Enhanced as well. If gamepad support turned on and there is Alternatte buttons set to Buttton#1- game can recognise KB multimedia as such Buttons#*.
Turn off gamepad support in options or remove alternate buttons from controls schema. And when you want to play Q2 Enhanced with controller if your is not Xbox/clone one - reset controls and re-set manually.
Some games come with Sony full support - recognise and pre-set controls for it. But Sony change HWID for differ revisions and newer recognised as Xinput Xbox pads instead (unknown HWID Xinput devices recognised as Xbox 100% clone even if buttons are differ, DX Dinput General PnP cannot be recognised which buttons it have just their B№#). Depend when game released and which ones HWIDs stored in input code as supported.

For old games default schemes never be a thing for non-KB input/multimedia devices. For original Quake 2. Same as all RTS it also do support gamepads cause support Dinput. But for such old games it is more. Wolf3d and some more older shooters did not really or at all support mouse. Quake 2 come when mouse almost become standard (with WASD keyboard default scheme in ingame's). But keep Q1 controls even for mouse which one come from Wolf3d that did not really support mouse. For original Q2 even mouse should be rebinded manually (default RMB, 3rd middle button and wheel default is useless). KB is only main input for PC games. Gampads as second and mouse as third should almost always be rebinded manually.

And even if no gamepad in use need to fiddle with Controls. Remove Button# from schema. But only if you have multimedia Keyboard (any additional buttons on it). Or maybe mouse with more than standard 3 buttons. No way OS recognise them not as MouseButton#* which is completely separate numerate from gamepads/KB multimedia. Or this is possible?