I understand why
Let is a mathematical statement that was adopted by early programming languages like Scheme and Basic. Variables are considered low level entities not suitable for higher levels of abstraction, thus the desire of many language designers to introduce similar but more powerful concepts like in Clojure, F#, Scala, where
var from the beginning, so they just needed another keyword, and just borrowed from dozens of other languages that use
let already as a traditional keyword as close to
var as possible.