I totally validate your feelings, Starrysky!
I have had a neighbor once refer to me as "kid" or "kiddo" and it was entirely to denigrate me. He was threatened by me because I had income and education in my mid-30s, and he was in his mid-50s, was a raging alcoholic, taking care of (or abusing, if you ask me) his dying mother, and hadn't held down a job in a decade, and couldn't hold one down before that either.
He would do light housekeeping for my other neighbor who I would have coffee with every morning, to earn a few dollars, and he would call me "kid," to which I would tell him not to call me that. I was not his friend, I did not have any relationship with him, and I was disgusted with how he would hit his poor, dying mother (dying of cancer).
The only time someone has called me "kid" and it hasn't been offensive was when I was dating my boyfriend who was 16 years older than me and we would jokingly call each other "old man" and "kid." But obviously we were very close and intimate, so it was lighthearted joking.
I say "I love you" to friends, but it sounds like he is not a close friend. If it makes you uncomfortable, then it makes you uncomfortable. You don't have to change your feelings. Feelings aren't wrong. They are just feelings.
It sounds like your mother just blew you off when you needed someone to talk to about it. I'm sorry she can't be there for you. I think, maybe, it's something you are going to have to expect with her, that she simply cannot validate you or give you the support you need.
Your feelings are valid though. I think, like me, there must be something about you that makes people think they can be very friendly or overly familiar with you when they don't really know you. I don't know if I have just an overly friendly face or something...
PM if me you need to. I'm here.

Seesaw