老 is a picture of an old person — long, unkempt hair on top, a bent body, leaning on a cane (the bottom stroke). It has meant 'old' for over 3,000 years, barely changing.
In Chinese, 'old' is a sign of RESPECT, not an insult. 老 prefixes warm, respectful terms: 老师 (teacher — 'venerable master', NOT 'old teacher'), 老板 (boss), 老朋友 (old/dear friend), 老人 (the elderly, honored). Calling someone 老王 (Old Wang) among friends is affectionate. Age = wisdom in Chinese culture.
Long hair, bent back, a cane — an OLD person.
老 in 老师 (teacher) doesn't mean 'old' — it means 'respected'. The same warmth is in 老板 (boss) and 老朋友 (dear old friend). In China, 'old' is honor, not insult.