It has so many names because it is so huge. While trombones have tubes, trumpets prefer to wear valves. A trumpet is an instrument when it is not an elephant sound. Another name for kettle drums is timpani. But I think I will just stick with the first name and learn it good.
Instruments come in many sizes, shapes and orchestras.
You should always say 'celli when you mean there are two or more cellos. A tuba is much larger than its name. A harp is a nude piano. My favorite composer is Opus. My very best liked piece of music is the Bronze Lullaby.