There have obviously been developments in trumpets over the years. The two main predecessors to the modern valved trumpet are the natural trumpet and the keyed trumpet (about both of which my knowledge is somewhat limited).
As trumpet players begin to get into orchestral playing, they may sometimes wonder why early pieces seem to have “boring” trumpet parts, always playing the same few notes. Little do they realize that this is because the instrument was severely limited. The natural trumpet had no valves, and this is also the reason why any trumpet part of any significance from the baroque is written in a high range. There is less distance between playable notes in the higher range of these trumpets.
The keyed trumpet was supposedly invented by Anton Weidinger, a trumpet player for which Haydn and Hummel wrote their concertos. This was around 1800, and while the instrument sounds like a natural trumpet in tone, it can play all the notes of the chromatic scale. The bore has openings which are closed by the various keys. The instrument is held differently than the modern trumpet, and four fingers of the player’s right hand must move between more than three keys, making it seemingly difficult to play.
I think it’s interesting to be able to hear how the concerto would have sounded in 1800 when Haydn composed it. Have a listen.