There were things here a billion years ago. There will be things a billion years from now.

No, there really won't be. The Sun is getting brighter as it ages, in just a few hundred million years Earth will either cook to death or every single molecule of carbon dioxide will have to be taken out of the atmosphere to counteract the effect. Either way photosynthesis ends at that point.

Unless something technological intervenes.

Also, a billion years ago the only "things" that were around were bacteria. The Cambrian explosion didn't happen until 530 million years ago.

Humanity is a blip that will be forgotten.

Unless our descendants are still around, which they could easily be. Humanity doesn't need Earth to survive long-term. The reverse is not true.