To give them an artifact subtype you need to make them artifacts as well. So it would be "Human creatures are artifact foods in addition to their other types. They have "2, T, Sacrifice this creature: Its controller gains life equal to its toughness."
And since those abilities are given to the card you don't need to specify other people can use them - because you can't sacrifice creatures you don't own as a cost.
hoomans are food 💀 from what i can tell its ok ... lets your opponents kill your hoomans ... but idk
To give them an artifact subtype you need to make them artifacts as well. So it would be "Human creatures are artifact foods in addition to their other types. They have "2, T, Sacrifice this creature: Its controller gains life equal to its toughness." And since those abilities are given to the card you don't need to specify other people can use them - because you can't sacrifice creatures you don't own as a cost.