The major languages for intellectuals, going back in time, Arabic was the language of science, then Greek, then German & French. (Roman = Latin), especially for the Western world, but one should not overlook Chinese and Japanese.
Regarding a second language, in chemistry German is the best second language. A lot of innovative chemistry is published in German (although it is probably not as dominant as it once was). In literature French & Russian are but many cultures have great literature, so I don't have strong feelings on that one. In business Chinese probably is by now. Russian is a great language for physics.
For a future global language: English is great at picking up words from other languages. Many languages will contribute a few words each, and the major languages will contribute many words each. English is a blend of many of the world's languages, and is likely to be more so.
Art is a compact way of conveying information. As such, it sits alongside language, genomes, etc., as something innate in a universe of sufficient complexity. It is a continuum, not an all or nothing thing.
This universe appears to obey principles that can be expressed using mathematics, so I look at mathematics as a tool/language for describing what the universe does. is our best shot at a universal language among technologically advanced species.