Most things in Thai have classifiers. Kon is the classifier for people.
Khun (polite) Jeen. Yes you could say Khun Jeen lay lay Khon. I don't think correct to say 'Person Jeen, many persons', but Khun Jeen 150 Khon is correct.
Anyway, no one much cares, but I call a Chinese person Khun Jeen and a Thai person Khun (name).
I call myself a Farang. ????