I only speak one fluently but I find languages fascinating. Not so much the speaking of them but the concept and origin. How did what appears to a non-native speaker to be a collection of random sounds become a method of communication across a community and in some instances, far beyond? There is no consensus on the origin of language in humans. In the 19th century the Royal Linguistic Society in London actually banned discussion of the origin of language as they felt the theories proposed and ensuing debate was so outlandish that it would be a waste of time.
The most peculiar aspect of language, and one that I struggled with throughout elementary school, is grammar - the arrangement of vocalizations into complex patterns to convey different meanings and contexts. Did all of this arise from a single grunt by one of our ancestors that evolved to a grunt of pleasure that eventually gave rise to a series of vocalizations that somehow conveyed the pleasure of eating a particular piece of ripe fruit?
I am thankful we have language to communicate although we could learn to do it more effectively within our families, communities, among countries and across the planet.