Let's start with the first option. It is possible that you may be asexual. There are many different shades of this term, but the underlying definition is the lack of interest in sex or less interest in sex than anything else. About a percent of the population identifies this, so it is important for you to know that asexuality is relatively common and completely normal.
Now, let's talk about the next option. You are relatively young and you have said that you will not describe yourself as a man of little sexual experience. It may take a while to understand what you like and to respond sexually. Indeed, most people would describe their early sexual experiences not so enjoyable. Perhaps you have not yet experienced the best sex of your life, so there is no reason for you to be excited. It would not make sense for you to die after something that was not good.
If so, then the solution is more exploration and experimentation. Right now, I will encourage you to explore your body yourself and try to understand what you like. Do you have a regular masturbation practice? If not, this may be an interesting thing for you to explore. You can also try reading erotic books or sex education and see if you discover anything that shows your interest. You can also start to create a list of sex sections of things you want to try at a different moment.
Many people have a very passive sexual approach but if you are not actively exploring and trying to understand what can make you feel good about your body, this will not bring any great benefit. During sex, have you ever caught yourself thinking that you want things to be different? Forget this fact and relax your body and mind.
It's all you need to feel the emotions of intimate act!