I'm not sure I follow. How is it gone? We have fusion (solar) and fission. And we may find out how to more directly harness energy as we progress. I think our access to energy is limited by our lack of knowledge.
I agree though, we should get out on some new space vessels soon to buy some insurance and project ourselves into the far future.
If we go extinct, the next intelligent species (if there is one) won’t have the easy reserves we used to get started. You can’t jump directly from fire to fusion.
That's not true: given enough time decomposing organic material will create new oil reserves, while all the metals excavated are still right here on the surface of the Earth used every day by us (cars, phones, ...) and ready to re-enter the surface once we are done using them.
