“If they haven’t succeeded, why should we?” This, I think, is the real root of an answer to “Will we reach the stars or not?”

It doesn’t matter whether there is only 1 species in the universe capable of doing math or one around every star if there isn’t a method to transfer between stars in a reasonable amount of time. The real question is if it’s possible to travel the breadth of the universe in less than the time it will be in existence?

Colonizing the universe is a somewhat meaningless question, it’s neither a necessary nor sufficient condition for the existence of other intelligent life. And the universe is so vast, there are so many stars, that occupying even a significant fraction of the inevitable planets seems implausible. Even given instantaneous transportation and infinite physical resources, how long would it take us to to generate a large enough population to put representatives on planets around 10^22 stars, or even a sparse sample like 10^10?

I think a far more interesting question would be “Will we ever explore our galaxy,” or “Will our species outlive our sun?” But these are much harder to answer, I think, than “Will we be able to populate infinity.”

Point #2 sounds rock solid to me.

“In the absence of humans, other species do not converge on human-like intelligence as a generic solution, or even a specific solution to life’s challenges.”

Replace humans with dolphins or crows or parrots or elephants, and the sentence is equally true (or wrong). For example:

“In the absence of dolphins, other species do not converge on dolphin-like intelligence as a generic solution, or even a specific solution to life’s challenges.”

Replace intelligence with wings:

“In the absence of bats, other species do not converge on bat-like wings as a generic solution, or even a specific solution to life’s challenges.”

Humans are more intelligent than dolphins. Bats are more wingy than flying squirrels. Intelligence has increased in several lineages as a response to the challenges of social life (itself being a response to resource clumpiness or whatever). Winginess has increased in several lineages as a response to the challenges of flying life.

Do these facts tell us anything about intelligence and winginess in other planets? Yes or not? If not, does life on Earth tell us anything at all about life in other planets?

a) Evolution shows no “penchant” for developing animals, let alone animal-like intelligence.

b) Terrestrial animals seem to show a penchant for bigger brains, but this tells us very little, because all terrestrial animals are relatively slight variations of a single common ancestor.

c) Even among terrestrial animals with a penchant for bigger brains, there is no apparent penchant for human-like intelligence.