I’d say the most exciting thing on the music horizon is AI. Who hasn’t wished for an app that could build a song around a riff or a few bars hummed from your mouth?

I have a collection of fragments that have magically appeared in my head over the years. I’d say, at least enough for an album if I had the skills to build songs around them. They’re just sitting there on my digital recorder waiting for the AI app.

The fact they appear once-or-twice a year is why I never considered trying to "monetize" them. I’m sure Paul Simon, Peter Gabriel, etc. get these inspirations weekly at least.

Here's something new:

Any instruments new or old, and there is an "uncountable "numbers of them , often not well known define music perception, because each one had his own "timbre"...

And the last discovery in acoustics demonstrated that this is  fundamental because "timbre" of instruments define  the way we will hear and understand music.

https://www.pnas.org/doi/full/10.1073/pnas.2308859121

https://phys.org/news/2024-02-pythagoras-wrong-universal-musical-harmonies.html

Now this very interesting documentary will illustrate what i want to say better than i could :

Çifteli: This microtonal instrument changed the way I think about music

To answer the OP questions there exist an incredible number of musical instruments all along mankind history...

This does not end....

"timbre" and "rythm" had no date no age and no programmed lifespan, they are meanings...

This Sumerian instrument sound anything save primitive...