I don't think that it is true that he hadn't really liked you. I find it hard to imagine anyone doing something so intimate as resting their head on your belly after sex if they don't like you.
From the evidence "no second date", it is a false, incomplete dichotomy to conclude that either "I messed up" or "he hadn't liked me". You yourself added a third option, "He is a player." which I suppose means someone who is just interested in "conquests" or quantity of ONSs. Though we would have to acknowledge some internal conflict on his part, either selfish - to keep you on his rolodex for a booty call, or uncaring (but then why even text?) or from not wanting sex/intimacy again with you for whatever reason but not knowing how to negotiate that openly.
Based on hearsay (the attempts to warn you - from what? good sex, intimacy for a night?) may indicate that he'd behaved like this with others, making him a player I suppose.
I have been in situations similar to yours (though on each of the 2-3 occasions it was after 2-3 ONSs) where the texting, calling or even in-person meeting went on, with lots of mixed messages (Don't want a relationship, not ready, but we can be friends, the sex was great, FWB of course, but not tonight, can you help me put these shelves together (this is Furniture Without Benefits)) but without ever again culminating in sex. Some remained friendish for a while. Luckily I have a close friend who early on pointed out that it was a waste of time trying to understand "Why?", that it would happen again, it had nothing to do with me or my actions, and to just move on, so it didn't take me two years to get over any of it. I hope you have a friend like that now.
I've also been the other party: had a ONS, kept texting, but never committed to another "date" or intimate meeting. I was attracted to her, enjoyed her company, but something about the sex didn't work for me. I didn't know how to avoid hurting her feelings, so I didn't ghost her, but I was noticeably stilted in our following texts and conversations. Again, luckily for me, she was a big and strong enough person to bring it up explicitly "if the sex didn't work, it didn't work, it happens". We were able to remain friends, she would tell me about her other dalliances and helped with me with some resume writing.