尔 was the classical 'you' — a character drawn from a loom's symmetric frame. Adding the person radical 亻 domesticated it into 你: the everyday second person, the character that starts more Chinese conversations than any other.
你好 is the front door of the language — the first phrase every learner speaks. Respect adds a heart below: 您 nín, 'you' with a heart underneath, for elders and customers. Choosing between 你 and 您 is a daily etiquette exam.
A person 亻 at the loom 尔 across from you — YOU.
你 acquired a gendered twin 妳 in early 20th-century writing (paralleling 她), but mainland usage dropped it — 你 covers everyone.