Tinsley is from the Old English Tynni's lēah — Tynni's clearing/meadow — historically a Yorkshire surname. Mortimer was one of the most-followed Manhattan socialites of the 2000s-2010s, frequently appearing in Vanity Fair, Vogue, and Town & Country — establishing the modern New York socialite archetype that later inspired similar TV shows. The name's modern surge through 2016 directly traces to Mortimer's Bravo appearances; it had been outside the US top-1000 before her TV debut. Tinsley also evokes the British connection — Tinsley is a village near Sheffield in South Yorkshire.
Tinsley does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Tinsley reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.