Every default player key: movement, weapons, inventory, actions, vehicles, communication and menus. Plus how to rebind them.
These are the default keys. You can rebind almost any of them: Esc → "Settings" → "Key Bindings" → FiveM. The inventory key and the action key are changed in F2. To see all your keys as they are bound right now, open F2 → "Settings" → "Keys".
action key. At the trunk of a car, helicopter, plane or boat: open it. At a player: the G menu (bandage, give blood, inject morphine, give antibiotics, handcuffs, escort, put in or pull out of a vehicle, search)
G while handcuffed
pick your own handcuffs, if you have a lockpick
mouse wheel
menus at a vehicle, tent, body, campfire or gate: the wheel picks a line, pressing the wheel or LMB uses it
F5
emote wheel: hold and release over an emote, or pick one with the mouse
H with night vision
turn night vision on and off, if the goggles are in your inventory
In the G menu: ↑↓ or the wheel pick a line, Enter, the wheel or LMB use it, Esc or G close it. If you carry a blood bag, "Give blood" is already selected.
Inventory: F2 → "Settings" → "General" → "Inventory": Tab, I or J. If you pick Tab, the player list moves to CapsLock.
Action key: F2 → "Settings" → "Keys" → "Action key" → "Assign", then press the new key (Esc cancels). Keys already in use can't be assigned: H, for example, is taken by hands up. "Reset to G" puts it back. The choice is stored on this computer only.