We had common ancestors with sea anemones. We weren't necessary anemones no more than anemones being humans. Parallel evolution led us here and anemones where they are.

> In a billion years you could have literally any lifeform currently on earth evolve into intelligent beings capable of spaceflight.

That depends on how likely is human-level intelligence to arise, so far only one species arrived there and no other. Then you add expectations of being able to build a spaceship capable of escaping Earth's gravity well.

Hoping some future intelligence can do job we can do now is ultimate form of procrastination.