To consider the Earth as the only populated world in infinite space is as absurd as to assert that in an entire field of millet, only one grain will grow.
None of us knows anything, not even whether we know or do not know, nor do we know whether not knowing and knowing exist, nor in general whether there is anything or not.
A single ear of corn in a large field is as strange as a single world in infinite space.
It is unnatural in a large field to have only one shaft of wheat, and in the infinite Universe only one living world.