Question: <https://www.google.com/search?q=western+musical+instruments>

Will it be very few western musical instruments that can be played by human beings with one hand only?

Example : Mouth organ.

Answer: 
Bugles are one-handed. Trumpets, tenor and French horns would be playable to *some* extent. The pipe of a pipe and tabor! Flexatones are lovely things. I've seen virtuoso bass guitarists play whole pieces with one hand.

At [OHMI](https://www.ohmi.org.uk/instruments.html) (One handed musical Instruments) there are all kinds of instruments and *adapted* instruments. The one-handed clarinets and Chapman Sticks look good. They also have supports for the trumpet and trombone.
Keyboard instruments such as piano, plucking instruments such as harp, .... many can be played with one hand only.