We’re talking about several different things here. The “bells and whistles” do not do much to how a person thinks; a Spanish speaker doesn’t care that a bridge is “masculine”. Some grammatical obligatory features more fundamentally require the speaker to develop a certain kind of specialized awareness, such as the absolute-direction languages.
But you seem more interested in “vocabulary” – and “access” to that differs as much from speaker to speaker of the same language as it does from one language to the next. Sure, there are ideas which one language has a word for and another doesn’t – “wabi sabi” in Japanese, etc., etc. – and these do usually reflect the importance some idea has for one culture. But the vocabulary doesn’t shape the mind, except at the margins.
Certainly, “complexity” has little to do with any of this. It is difficult to measure “complexity”, and one language is usually complex in some ways and not others, while the next language is complex, too, but in different ways.
There are sometimes (debatably) a few ways that complexity can be measured overall, and “creolization” (to put it in an oversimplified way, parents having to use a second language to speak to each other, and their children speaking the result as a first language) will simplify a lot of things pretty consistently (English is more creolized than other Germanic languages except for Afrikaans, e.g.). “Indigenous” languages, spoke by relatively few people, will thus tend to retain the most “complexity”, in many ways. But I doubt you would contend that German speakers have more access to complex thought than English speakers, and Navajo speakers more than Germans.
What do you mean by the “vocabulary” of a language? The sum total – lexicon – of all words used by all its speakers? Spoken, or written? Which dialects do you include? How much technical vocabulary do you include? How do you define any one person’s “access” to some defined portion of the total potential lexicon? This may be a useful exercise for some reason or another, but not, I’m almost sure, for better predicting how a person’s mind works, or what they are capable of thinking, or even what they are likely to think (except to the trivially obvious extent that a language’s culture and geographic setting, and the things it has words for, will show much correlation for certain kinds of words.)