"Shelley is a people loving person" is acceptable. A person who likes other people does not have to be sociable or popular, though some are that way.
I am wondering if it's acceptable (grammatically & colloquially and NOT in anyway weird) to say "people loving person."
I am aware that "people person" exists but it seems to convey the feeling that the person is not only sociable but also popular.
"Shelley is a people loving person" is acceptable. A person who likes other people does not have to be sociable or popular, though some are that way.
I'd use a hyphen: a people-loving person.
Context is important. Please provide enough for us to be able to deal effectively with your question.
Your thread title should include all or part of the word/phrase being discussed.
If you just want to know the meaning of a word, try OneLook Dictionary Search first.