Of the 141 human language families, I know only two: Indo-European and Austronesian. I have traveled, but only to places where three other families are spoken: Japonic, Uralic, and Sino-Tibetan.
Within Indo-European, I can communicate to some degree in Classical and Koine Greek; French and Spanish; and English — twigs within the Hellenic, Italic, and Germanic branches of that family tree. I have forgotten more Classical Latin and Russian than I learned in classrooms, and have a tourist’s knowledge of Italian, Icelandic, and Standard German.
This map and this family tree display the vastness of my ignorance. Except for Tagalog, my ability to communicate is entirely confined to the Indo-European family. Even within that tree, I completely lack knowledge of the extensive Indo-Iranian branch, as well as of Celtic, Armenian, and Albanian. While I can often infer the meaning of a word when I travel in Italy, that is more difficult for me in Iceland or the Czech Republic, and impossible in Wales.
Meanwhile, human languages are only a small part of knowledge! There will always be something I do not comprehend. But consider the alternative: to be omniscient, to know everything, to be unable to learn. How boring that kind of life would be, that life would be death.