First time happening to me in 4 years.

So I am 16 now and never had a boyfriend or been asked out or something. Some people showed me that they kinda liked me but never told me. So about a week ago I got a message from a boy (18 years old). I didn't know him or spoke to him in person but he is a boy from my school. It started with a 'hi' which made me so nervous it took me 3hrs to reply. Then he said 'How are you?' and I replied 'Fine, how about you?' and he said 'I'm good'. At first I thought it was a joke and I replied just to be polite. He ended up telling me this: 'Anyway, i saw you and i liked you and I would like to get to know each other better if you would like it as well'

I never answered until now because I am not interested and also because I didn't know if this was a joke or anything. Not that he is not handsome or something, I just feel that at my age this shouldn't be my priority. I can think of a boyfriend later on but now it's not the time. With the 'no reply' i thought i would show how serious and decent person i am. If I replied i could be made fun of or even make him feel even more awkward or something. What do you think? Did I do right or should I say something else? Should I feel bad now? Please tell me your opinion x