Is or Are

No

I am, you are, he/she/it is, we are, you are, they are !

You are answering your own question. YOU ARE HE IS SHE IS, etc. HE IS WELCOME, YOU ARE WELCOME.

I understand your question, and you are right; it is weird. I think the origin of "you ARE" (even though you're talking to a single person) is politeness. For some reason, speaking to a person using words for many people was polite. In French, there is a singular 'you' and a plural 'you'. When talking to a stranger, people use the plural 'you', because it is polite. This leads me to suspect that

In English, "you" is plural when refers to either one person or many. We cannot change the traditional usage of a language.

In the southern US, people still say 'you is', especially older people. I find it endearing. Obviously 'you are' is correct. Isn't language great?!

second person singular of the verb to be is you are. your is a possessive pronoun meaning belonging to you.

The word 'you' in English is a strange one, it is actually the formal reference for a person or persons, there was once another 'informal' word being Thou, so to one person you would say "Thou are", to more than one you would say "You are", we dropped the Thou many years ago but kept the structure.
Also, the English language is Germanic/Norse in origin but our grammar rules are Latin and a