That's a great question !
The answer is:<em> It does !</em>
A push on an object causes the object to <u><em>accelerate</em></u> in the direction of the force.
The <em>less</em> mass the object has, the <em>more</em> the force accelerates it.
Now, when you jump, the forces on you and on the Earth are equal forces.
The up force on you causes you to accelerate up by some amount.
The down force on the Earth causes the Earth to accelerate down by some amount.
The Earth's mass is something like 5,972,000,000,000,000,000,000,000 kg, while your mass is something like 50 kg.
The Earth has something like 119,400,000,000,000,000,000,000 <em>times</em> as much mass as you have.
So your acceleration is something like 119,400,000,000,000,000,000,000 <em>times as great as the Earth's acceleration.</em>
==> The Earth's downward acceleration, caused by your jump, is there. It's just too small to notice.
<em>BUT . . .</em> That's the reason why seismometers (instruments to detect and measure the vibrations from distant earthquakes) have to be located as far as possible from cities and busy roads.
In places that are too close to cities and roads, the Earth's surface is always vibrating, wiggling, jiggling, heaving and weaving, in reaction to the forces of people walking around, cars and trucks driving around, even rain falling down. And kids jumping up and down !
In such places, these people-motions are louder and stronger than the vibrations coming from distant earthquakes. Seismometers wouldn't work there.
