Newton's third law is sometimes summarized as "for every action, there's an equal opposite reaction" but when you jump from earth, the earth doesn't jump backwards from you. how does newton's third law of motion apply?

When you want to jump UP, you push DOWN on the Earth. Then, because of Newton's 3rd law, the Earth immediately pushes UP on you, and this equal, opposite REaction is the force that lifts you up.

By the way . . . . . The question is wrong, wrong, wrong.

When you jump up from Earth, the Earth DOES jump backwards away from you.