instagram sucks- advice needed urgently

Today I was at the train station and this guy thats always there was watching me scroll through instagram which first of all like what happened to privacy but anyways he said "you can add me on instagram and we can message each other" and guys i barely know this man like i didn't even know his name until he showed me his instagram and when he approaches em and my friend at the train station he basically just talks at u rather than to u but like i said okay bc what r u meant to say in this situation but anyways i added him and he watched me accept his follow request (i added him on my old acc not my usual one LOL) and then he touched my hair and told me i should get it cut shoulder length (my hair is like waist length, i straightened it today lol) and i hate ppl touching my hair sm so that annoyed me a bit but the he said i needed to vote today or whatever and i said i cant because im 17, im underage so i cant vote and he was like oh. Then the train got there (think it was literally me, him and one other person even at the train station lol) and he told me i could sit with him on the train and i was like sorry im gonna sit further back bc i dont like sitting in the front carriage and he was like okay ill message you and he messaged me hi when i was in class so i responded with hi lol bc i use lol religiously and then i was telling my friend about this and i discovered that a notification hadnt been sent to me but he had messaged me the sentence "i really fancy you" and guys i found his facebook and he is THIRTY (i think, 29 if not) and i literally TOLD him i was 17 today so like no excuse but also why would he even say this because not once have i been anything more than polite, not even very friendly i dont think, and im literally clapped so wtf. He literally doesnt know anything about me like tf??

so anyways that was at like 10AM today and i havent responded its been 12 hours what do i say to him- here r the facts:

1. I dont think i even like men

2. If i did like men he wouldnt be my type

3. he literally knows nothing about me

4. he is a grown man

what should i do about this? i have to get the train tomorrow so i will probs be there with him for half an hour most of that time very much alone so itll be so awkward. how do i reject him? the summer holidays start next week thank god but i usually get the train at the same time as him 3-4 times a week. Its just so cringy

On a more embarrassing note, i was sending the most heinous instagram reels i could find to my friendf but misclicked and sent a video about JFK giving head and backshots to someone else and didnt realise until they responded pls kill me