I'm having trouble of deciding on what to invest in? Stocks, crypto, bonds, EFT or gold?

I'm 16 years old and today in class, there were two successful traders and entrepreneurs educating us about investments, side hustles, businesses etc (things that I have basic knowledge in). I stayed there to ask them a few questions and ended up being the last to leave. One of them said that I should be diverse since it puts at a lower risk of not making money of one asset since I would have other assets that would make me money. But I tend to overthink and think that I should invest in all of them but I'm not quite sure on what I should do. Please answer if you can