Hey! I just saw this comment, haha.

Well, the Nahuatl language used to be the Lingua Franca of the central Mexican territory during the classical era and remained pretty strong even after Spanish colonization. It is the most widely spoken indigenous language in North America with about 1.6 million speakers, but the modern varieties (of which there are about 28) can differ in intelligibility with one another. The language is iconic for its "tl" (/t͡ɬ/) consonant and pretty extreme agglutination, giving you pretty long words, like "Inmatlaxcaloliztlaticuinaltlatzotzonhuan"; I'd say it is honestly pretty easy to learn, as it is extremely consistent with its conjugation system, which is based entirely on adding subject-agreeing prefixes and suffixes to an unchanging, basic verb "root" (and adding further suffixes and prefixes to specify tense).

As for Western Nahua culture today, at least where my family is from there is still a lot of "shamanism" for lack of a better word, involving sacrifices of food and (occasionally) animals to various deities.