Your analogy to a stripped back version of JavaScript is really on point. I feel that way about Lua too. Through time Lua kept its simplicity, whereas ECMAScript kept accreting stuff which most of the times makes life easier, but also gives way too many choices for how to do the same thing.
Indeed the 1-based indexing, which often generates heated discussions, could be a source of confusion later on. However, like you mentioned, it can also prompt the beginner to quickly understand the languages are just tools, which have slightly different ways to be used, depending on what they're trying to solve.
In fact, this 1-based indexing is by convention (although everyone uses it), once again showing how flexible and "hackable" Lua is.
I often hear this (probably because PIL is so optimistic about it), but I would say that 1-based indexing is not just a convention, it's a default that's baked into the language:
And there's more: built-in functions like ipairs will not work with hacked-up zero indices (which you would have to specify every time you create an array). Overall, straying from the default is not a great idea unless you really need to (like in LuaJIT).