If you want to entertain yourself, of course you don’t need to pursue advanced knowledge of music theory. If you want to learn a solo instrument, there are many options. For those with a more melodious sound, I think it’s the flute. Xiao is also relatively melodious, but always feels a little melancholic. However, it is not easy to learn wind instruments. You must first learn to breathe. The requirements for breath are also very strict.

I am a piano player, and I often play the piano at home to soothe my emotions. I personally think that the piano is also a good choice, but it is quite boring when you first get started.

As for the question of which instrument is easier to learn, it’s really hard to answer. Because it is easy to learn an instrument, but every instrument is not easy to learn well.

Based on personal experience: I recommend you learn piano. Let’s start with Beyer, which is the most basic tutorial. Don't be too quick, be solid. Wait until the foundation is solid before you can move forward.

If you want to learn piano or electronic keyboard, I can help you. I can’t help you with other instruments! I wonder if my answer can inspire you?