In the Original Star Trek series, or perhaps the later series, is it ever explained why aliens always understand earthlings? Do they have translator devices (not seen or mentioned)?
Or is it due to the obvious difficulty of subtitles and languages?
As I said, if you spoke to someone from the past, they would speak English differently to you. Have you ever seen any Shakespeare?
Of course Aliens in Space understand English. They are not stupid!
Seriously, it is from our television and radio broadcasts which leaked out into space, intercepted by their probes and relayed to their home planets. Ever see the old Spielberg TV show where space aliens come to earth hoping to meet our leaders- Lucy Ricardo and Ralph Cramden?