Earths orbit around the Sun is elliptical not circular as most people think. What is more important, is the fact that the changes orbit every 100 million years, from circular to elliptical. This causes, what we now know as, ice ages. The distance from the Sun is increased cause exaggerated temperature changes throughout the planet.  If we, the Human race, are not prepared for this, it could be our undoing.

If our orbit becomes too elliptical, our summers will be heat blasts, the like of which we have never seen. Our winters would be a mini ice age. This would have the effect of killing our crops and livestock. Without these we as a race would become extinct.

Have said all this, there will always be a form of life here, maybe not us but there will always be life here. Even in the most extreme case, where our planet was to lose orbit altogether, life would continue. Our good friend and enemy, the bacteria.

The human race is but a bump in the evolution of our planet. The rest of the Universe would not even notice our species disappearance from our little Galaxy.

At best the human race will become a footnote in some future or Alien archaeological study.