I think that a language for beginners should be as paradigm agnostic as possible. Lua does not force OO or functional programming upon the user. And unlike Ruby, there aren't a bunch of list-like datatypes like lists, arrays, and hash tables to keep track of. There is just the table datatype which takes care of all of those.
Lately I lament that Python, Perl, Ruby and PHP are the dominant scripting languages instead of Lua. None of the former really justify their extra complexity, IMO.