The Earth has a lifespan? Really?

This may just be an exercise in terminology. The Earth is pretty much a closed system. There are a finite number of atoms and those atoms are being constantly changed into different forms/elements in the chaotic conditions.

When you say the Earth has a finite lifespan what is probably meant is that the Earth in its current form has a lifespan, just like humans have a lifespan in that specific form. It is not going anywhere, it's atoms will always be here, but they may end up in a different form.

If enough of those atoms are Hydrogen and Oxygen bonded together as water, and if the sun keeps providing its gentle warmth, then the conditions for life will always be here.

Humans, imo, are not evolved from this Earth. The true "mankind" life form of this planet were the Neanderthals but I believe they were overtaken, overrun by a foreign life form that was seeded on this planet by others. We are the aliens here.

The scenario of a planetary catastrophe occurring and a race of people fleeing to the stars has already happened. That race fled from Mars to Earth a long long time ago, leaving behind their cities and rivers and pyramids for all to see.
The colonisation of Earth took place about 17,000 years ago imo and is recorded in the Masonic tracing boards together with the whole story regarding the star system in the vicinity of Pleiades.

Humans have lost the knowledge of their origins and ancestry and instead have been fed a load of absolute cobblers. We don't belong here, which is why everything we do is not in harmony with Nature. As the film The Matrix suggests, we are a virus, a plague that spreads across the planet, ransacking its resources until they are gone, and then moving on to the next area to rinse and repeat. In the end, Nature will deal with us. Nature will outlast us by many trillions of years.