Water was home to the earliest life forms, the prokaryotes, simple cells without nuclei.
"There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved."
Charles Darwin, Origin of Species, 1st Edition (1859)