Does a creature that loses all abilities also lose keyword abilities granted by equipment?

When an effect says a permanent "loses all abilities," it removes every ability the creature currently has, regardless of where those abilities originated. This includes abilities granted by Equipment, Auras, or other continuous effects. The key point is that granted abilities become part of the equipped creature's set of abilities (CR 303.4f for Equipment, CR 611.3 for continuous effects applying abilities).

Continuous effects are applied in a specific layer order (CR 613). A "loses all abilities" effect operates in Layer 6 (ability-removing effects). Equipment granting abilities also functions in Layer 6. Whichever effect has the later timestamp — or is otherwise higher in the dependency/layer order — will determine the final result. Typically, if the "loses all abilities" effect is applied after the equipment's grant, the creature ends up with no abilities at all.

It is important to note that the Equipment remains attached; losing abilities does not cause the Equipment to fall off. It simply means the creature does not currently benefit from any abilities the Equipment would grant (CR 303.4e). The Equipment's own abilities (such as its equip cost) remain on the Equipment card itself, unaffected.

Concrete example: Your creature equips a Sword of Fire and Ice, which grants protection from red, protection from blue, and a triggered ability. You then cast Humility, which makes all creatures lose all abilities. Your creature loses the protection abilities and the triggered ability granted by the Sword, even though the Sword is still attached. The Sword's equip ability on the Equipment card is unaffected.